radiant edu primer rev b - personal.utulsa.edualexei-grigoriev/radiant... · sonar, medical...
TRANSCRIPT
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Teaching Electro-Ceramics
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
AbstractRadiant Technologies has created the Radiant EDU a simple low costlaboratory instrument with matching ferroelectric capacitor samplesspecifically for the purpose of introducing electro-ceramics to science andengineering students The unit is designed to study ferroelectric devices aswell as sensors and memories made from these components
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The EDUThe Radiant EDU consists of an arbitrary waveform generator (AWFG) anelectrometer and an oscilloscope integrated into a single unit controlled byan on-board microprocessor that receives requests from the host computervia USB communications
The EDU does not have an enclosure in order to avoid theperception by students that it is a ldquoblack boxrdquo
The EDUmeasureshysteresiscurves onpackaged
ferroelectriccapacitors
Student projects can be operated using the externalport
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
System FunctionalityThe external port containing the AWFG stimulus signal the electrometerinput and the oscilloscope input allows students to fabricate their ownexperiments or design and test their own sensors
A homemade force sensor forthe EDU built at Radiant
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
FerroelectricityFerroelectric materials like Lead Zirconate Titanate (PZT) or BariumTitanate are complex oxides with highly non-linear properties Theyexhibit polarization hysteresis and sensitivity to force displacement andtemperature changes They are useful as memory materials and assensors
-20
-10
0
10
20
30
40
50
60
-75 -50 -25 00 25 50 75
Classic Polarization Hysteresis( 025u thick PZT ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
With packaged PZT capacitorssupplied by Radiant thestudent can explore theprinciples of capacitance theelectrical properties ofmaterials memory andsensors
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
AbstractRadiant Technologies has created the Radiant EDU a simple low costlaboratory instrument with matching ferroelectric capacitor samplesspecifically for the purpose of introducing electro-ceramics to science andengineering students The unit is designed to study ferroelectric devices aswell as sensors and memories made from these components
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The EDUThe Radiant EDU consists of an arbitrary waveform generator (AWFG) anelectrometer and an oscilloscope integrated into a single unit controlled byan on-board microprocessor that receives requests from the host computervia USB communications
The EDU does not have an enclosure in order to avoid theperception by students that it is a ldquoblack boxrdquo
The EDUmeasureshysteresiscurves onpackaged
ferroelectriccapacitors
Student projects can be operated using the externalport
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
System FunctionalityThe external port containing the AWFG stimulus signal the electrometerinput and the oscilloscope input allows students to fabricate their ownexperiments or design and test their own sensors
A homemade force sensor forthe EDU built at Radiant
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
FerroelectricityFerroelectric materials like Lead Zirconate Titanate (PZT) or BariumTitanate are complex oxides with highly non-linear properties Theyexhibit polarization hysteresis and sensitivity to force displacement andtemperature changes They are useful as memory materials and assensors
-20
-10
0
10
20
30
40
50
60
-75 -50 -25 00 25 50 75
Classic Polarization Hysteresis( 025u thick PZT ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
With packaged PZT capacitorssupplied by Radiant thestudent can explore theprinciples of capacitance theelectrical properties ofmaterials memory andsensors
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The EDUThe Radiant EDU consists of an arbitrary waveform generator (AWFG) anelectrometer and an oscilloscope integrated into a single unit controlled byan on-board microprocessor that receives requests from the host computervia USB communications
The EDU does not have an enclosure in order to avoid theperception by students that it is a ldquoblack boxrdquo
The EDUmeasureshysteresiscurves onpackaged
ferroelectriccapacitors
Student projects can be operated using the externalport
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
System FunctionalityThe external port containing the AWFG stimulus signal the electrometerinput and the oscilloscope input allows students to fabricate their ownexperiments or design and test their own sensors
A homemade force sensor forthe EDU built at Radiant
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
FerroelectricityFerroelectric materials like Lead Zirconate Titanate (PZT) or BariumTitanate are complex oxides with highly non-linear properties Theyexhibit polarization hysteresis and sensitivity to force displacement andtemperature changes They are useful as memory materials and assensors
-20
-10
0
10
20
30
40
50
60
-75 -50 -25 00 25 50 75
Classic Polarization Hysteresis( 025u thick PZT ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
With packaged PZT capacitorssupplied by Radiant thestudent can explore theprinciples of capacitance theelectrical properties ofmaterials memory andsensors
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
System FunctionalityThe external port containing the AWFG stimulus signal the electrometerinput and the oscilloscope input allows students to fabricate their ownexperiments or design and test their own sensors
A homemade force sensor forthe EDU built at Radiant
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
FerroelectricityFerroelectric materials like Lead Zirconate Titanate (PZT) or BariumTitanate are complex oxides with highly non-linear properties Theyexhibit polarization hysteresis and sensitivity to force displacement andtemperature changes They are useful as memory materials and assensors
-20
-10
0
10
20
30
40
50
60
-75 -50 -25 00 25 50 75
Classic Polarization Hysteresis( 025u thick PZT ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
With packaged PZT capacitorssupplied by Radiant thestudent can explore theprinciples of capacitance theelectrical properties ofmaterials memory andsensors
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
FerroelectricityFerroelectric materials like Lead Zirconate Titanate (PZT) or BariumTitanate are complex oxides with highly non-linear properties Theyexhibit polarization hysteresis and sensitivity to force displacement andtemperature changes They are useful as memory materials and assensors
-20
-10
0
10
20
30
40
50
60
-75 -50 -25 00 25 50 75
Classic Polarization Hysteresis( 025u thick PZT ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
With packaged PZT capacitorssupplied by Radiant thestudent can explore theprinciples of capacitance theelectrical properties ofmaterials memory andsensors
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant TechnologiesRadiant Technologies Inc is the worldrsquos leading manufacturer of testequipment for electro-ceramics Our test systems can actuate 10KVdevices or measure the hysteresis of a thin ferroelectric film capacitor withdimensions less than a square micrometer
A submicron PZT capacitor courtesy of theUniversity of Maryland
045u^2 PZT 4060 PZT Capacitor
-80
-60
-40
-20
0
20
40
60
80
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
VoltsP
olar
izat
ion
(uC
cm^2
)
064u x 07u
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
PhilosophyNon-linear capacitors are an exciting technology used in almost everyaspect of society today Civilization would not function without themSonar medical ultrasound fire detectors infrared camerasaccelerometers medical sensors mechanical actuators microphones andintrusion detectors are just a few of the devices using non-linear capacitorsas the critical operating element Yet these very special capacitors arepractically unknown by engineers or even physicists and chemists
Radiant Technologies created the EDU to make the technology accessibleto university students and encourage them to pursue careers studying non-linear capacitors or building useful circuits with these unique devices
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Read MoreFor a narrative on the EDU and its applications click on the link below tojump further into this file
Primer on the Radiant EDU
You may contact us with questions or recommendations for the EDUandor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinezndash e-mail radiantferrodevicescomndash Telephone 505-842-8007ndash Fax 505-842-0366ndash web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Primer on the RadiantEDU Educational Tester
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Overview
bull Hardware Design
bull Circuit Architecture
bull Graphical Userrsquos Interface
bull Charge Measurement
bull Ferroelectric Capacitors and Sensor Chips from Radiant
bull External Sensor Projects
bull Oscilloscope Operation
bull Syllabi
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Designbull The test circuitry in Radiantrsquos EDU is implemented with modern surface
mount technology and components to reduce costsbull A USB communications port connects the tester to a host computerbull Standardized ferroelectric capacitor samples connect to the tester
through a built-in TO-18 transistor-type socket
Capacitorunder test
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Circuit Architecture
bull The EDU has one plusmn10V output and three synchronously captured 12-bitinputs Its execution clock is 50micros
To Host
Oscilloscope Input
Digital toAnalog
Converter
Analog toDigital
Converter
Cap A
48MHz 8051Microprocessor
with USB engine
On-boardPower Regulators(plusmn15V 5V 33V)
Electrometer
AmpUSB
Power Pack(18V AC) Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hardware Design
Microprocessor
PowerCharge Measurement
Digital-to-AnalogConverter
Stimulus Voltage
Analog-to-DigitalConverter
Cap AB Switches
OSC Port
PackagedSampleSocket
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple Graphical Users Interfacebull Only one measurement task is
necessary Charge vs Voltage vs Timendash 100Hz to 1Hz frequency rangendash plusmn10V range
bull A separate waveform task allowsrecovery fatigue and imprint tests to beexecuted manually
bull All file formats and export formats are inASCII but plots may be pasted from theGUI directly into other programs
bull Plotting options include derivatives andmeasurements vs time
Next page
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Simple GUI
bull Four parameters define the test profile The capacitor values can range from~10pF to 1nF Plus there is an on-board mux to select between Cap A andCap B in the packaged parts
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Data Plotting
Despite its simplicity the EDU has a powerful set of plotting tools All of the datadisplayed on the following pages was taken with an EDU formatted using EDU plottingtools and then copied from the EDU GUI directly into the presentation
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Measuring a Linear Capacitor
Plots of the voltage stimulus produced by the EDU (called the Drive) versus the chargegenerated by a linear capacitor in response to the stimulus shown The linear capacitor iswell linear
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
EDU Bipolar Stimulus Voltage[ 10ms Period ]
Driv
e V
olts
Time (ms)
-50
-25
00
25
50
0 1 2 3 4 5 6 7 8 9 10
Measurement of a Linear Capacitor[ 1nF Polystyrene ]
Cha
rge
(nC
)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the Linear Capacitor
Plotting the measured charge against the voltage on the X-axis yields Q = CV The slopeof the line is ldquoCrdquo the capacitance This is ldquohysteresisrdquo data albeit with zero hysteresis
-5
-4
-3
-2
-1
0
1
2
3
4
5
-5 -4 -3 -2 -1 0 1 2 3 4 5
[ Charge vs Voltage ]
Cha
rge
(nC
)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A PZT Capacitor
This is a lot more interesting The ferroelectric material translates the stimulus into acompletely different set of temporal frequencies
-75-50-2500255075
0 1 2 3 4 5 6 7 8 9 10
[ 10ms period ]
Driv
e V
olts
Time (ms)
0
25
50
75
0 1 2 3 4 5 6 7 8 9 10
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Hysteresis of the PZT Capacitor
Plotted versus voltage a real hysteresis emerges
-40
-30
-20
-10
0
10
20
30
40
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials have very complex geometric structures for theiratoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Click on the link to give a short tutorial on the origin of the ferroelectrichysteresis
The Origins of Hysteresis
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Packaged Ferroelectric CapacitorsRadiant has designed small packaged ferroelectric capacitors specificallyto work with the EDU The packaged capacitors make it possible for aclass to study and use ferroelectric properties in the lab
ndash Two capacitors to each package
ndash Capacitor sizes range from 100000 square microns down to 100 squaremicrons
Top view
COMMON CAP A
CAP B CASECap A Cap BCommon
TO-18 Can
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Packaged Die
bull 026micro 2080 PZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 5V saturation
bull Will withstandunlimitedexposure to 9V
10000 square micron capacitor
Contact Pad in GoldPZT
14mm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Building Gadgetsbull The EDU has a built-in port accessible with standard 6-line telephone
cable and telephone jack plugs to allow students to build their ownprojects and operate them using the EDU software
bull The external port on the Radiant EDU has the following signals
ndash plusmn10V AWFG outputndash plusmn10nC electrometer inputndash plusmn10V oscilloscope inputndash plusmn15V power and system ground
bull Using these signals the student can build his or her own gadget powerit stimulate it and measure it from the EDU
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Projectsbull Below is short list of interesting projects that can be built
and operated with the EDUndash Traditional Sawyer Tower measurement circuit for ferroelectric
capacitors
ndash FeRAM emulatorbull FeRAM = Ferroelectric Random Access Memory
ndash Air gap metal plate capacitor
ndash Force sensor
ndash Heat sensor
ndash Acoustic sensor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Diebull 10micro 42080
PNZT
bull Platinumelectrodes
bull TiOxSiOx ILD
bull ChromeGoldmetallization
bull 15V saturation
bull Will withstandunlimitedexposure to 36V
bull Can be solderedto PC board
4mm x 4mm PZT capacitor with 1microthick PNZT Piezoelectric Constant ~ 500pCN Pyroelectric Constant ~ 22nCdegC
Top and bottomelectrodecontacts
05cm
10cm
Radiant also manufacturers a large PZTcapacitor suitable for building simple forceand heat sensors by hand
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
Go to the following link for a very short explanation of the sensorproperties of ferroelectric materials
The Origin of Sensor Properties
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Sensor Board for EDUbull Radiant supplies a sensor board compatible with the EDU
external port that uses the sensor die shown earlierndash A charge amplifier powered from the EDU and connected to the sensor
capacitor converts any piezoelectric or pyroelectric stimuli to a voltage onthe oscilloscope input
Sensorcapacitor
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull The real time oscilloscope software supplied with the EDU can capture signals as fast as
2KHz or as slow as 10Hz and display data taken over 10 minutes or more
The plotshown is thecarotid arterypressure waveat the neckcaptured withthe EDUsensor boardconfigured tobe a forcesensor
ldquoDownrdquo means compression ofthe sensor capacitor ~1V1N
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Real Time Oscilloscopebull By extending the time scale to the human time frame it is possible to watch the flow and
ebb of heat around the sensor
A sine wavemade bynearby cupsof coffee andice waterinterrupts theserenity of anEDU sensorconfiguredfor detectingradiant heatThe room airconditioningcaused thewiggles
Coffee IceWater
IceWater
CoolerCoffee
Sensitivity ~ 02ordmCVoltSample Distance ~ 10cm
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Tutorials and Syllabibull Radiant has created a set of tutorials and guided experiments for
the EDUndash Eight lessons describe the physics of the dielectric constant linear
capacitors paraelectric capacitors and ferroelectric capacitors
ndash The first five experiments familiarize the user with the EDU and its tools
ndash The remaining experiments explain remanent polarization and memorysensors test procedures for electro-ceramics and reliability of electro-ceramics
ndash They are installed automatically with the EDU software
bull Professors are welcome to submit their own contributions to thetutorials or to publish their own syllabi for the unit
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Contact InformationWe hope that you have enjoyed our tutorial about the Radiant EDUYou may contact us with questions or recommendations for theEDU andor new ferroelectric-based components
ndash Sales information Michelle Bellndash Technical assistance Joe Evans or Bob Howardndash Shipping instructions Geri Martinez
bull e-mail radiantferrodevicescom
bull Telephone 505-842-8007
bull Fax 505-842-0366
bull web site wwwferrodevicescom
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Short Tutorial on theOrigin of Hysteresis in PZT
Radiant Technologies Inc Albuquerque NM USAradiantferrodevicescom
Rev BAugust 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Why does Hysteresis Happen
All solid materials are held together by a balance of electrical forcesbetween the atoms in the material lattices Normally atoms in a latticearrange themselves so that all of the electrons and protons cancel eachothersrsquo electric fields
Ferroelectric materials exist with a very complex geometric structure fortheir atoms This complexity gives rise to asymmetries in the lattice thatprevent all of the electrical fields of the electrons and protons fromcanceling each other out even though there are an even number ofelectrons and protons From these asymmetries arise all of the usefulproperties of ferroelectric materials
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Lattice and its BondsDiamond has a trihedral structure withsymmetrical covalent bonds betweenall carbon atoms
PZT has a tetragonalstructure with asymmetricalpartially ionic bondsbetween the oxygensand the metals
Symmetrical lattice + covalent bondingmeans no net electric fields
DIAMOND
Carbon
Lead
Titanium (or Zirconium)
Oxygen
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The electrons surround each atom equallyin time and space Hence there are noseparated charges for an electric field toact on Diamond has a low very lineardielectric constant ~56
The carbon atoms in diamond are about15Aring apart along an edge Each carbon atomoccupies about 1Aring So as temperature goesdown there is plenty of room for the carbon atomsto move closer without bumping into each otherDiamonds electrical properties are uniformover a wide temperature range
Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Perovskite LatticeIn the perovskite structure most ferroelectric materials haveno metals are bonded to metals Every metal is bonded onlyto nearby oxygens The bonding diagram looks like this
The electrons stay near the red oxygensgiving every metaloxygen pair a netelectric dipole An external electricfield will repel the metals and attractthe oxygens severely distortingthe lattice as it expands
Since dielectric constant depends onphysical ldquoDisplacementrdquo (the ldquoDrdquo in Maxwellrsquos equations) perovskitescan have huge dielectric constants as high as 30000
- -
-
-
-
-
++
+
++
+
+
+
+
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The TitaniumOxygen CageAn easy way to visualize the distortion is to lookat the effect of a field on the TitaniumOxygen sub-lattice
+-E
The LeadOxygenlattice also distorts
+-
--
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Coefficient of Thermal ExpansionAll solids can be treated as a network of balls and springs
Temperature is simply the motion energy of each atom The higher thetemperature the faster they move theharder they bounce off each other and
the further apart they force each other to stay Hence physical sizeof solids changes with temperature The change in dimensions vsthe change in temperature is the Coefficient of Thermal Expansion
The CTE of PZT is ~15 times that of Diamond
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Remanent PolarizationPZT has a 4Aring lattice constant but many moreatoms are squeezed into the that volume than with diamond Asthe temperature drops and the lattice shrinks eventually thereis not enough room for all the atoms in the symmetricalformat So the lattice distorts to squeeze the atomscloser together A simple model is that thethe body-centered atom slides up about 005Aring soit is no longer co-planar with the oxygens
Since the titaniumrsquos electrons stay mostlyaround the oxygens a net vertical dipole is created
Note P = Q x d ~ 100microCcm2 for PZT unit cell
+
-
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Finally HysteresisOn many materials called ldquoelectretsrdquo the lattice is rigid and the internaldipoles are fixed relative to the lattice never to switch Ferroelectricmaterials on the other hand have just the right amount of softness soexternal forces like an external electric field can make the charged atomsshift position to line up with the voltage but the right amount of rigidity sothe resultant dipoles stay lined up when the force is removed at zero volts
Q
V
The next page shows howdipoles make this ldquohalfrdquohysteresis loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
The Electrical Measure of Hysteresis Negative Charge Positive Charge
(a)Dipole
starting atzero volts
+
-
CurrentMeter
(b)Apply voltage andcharge capacitor in
opposite direction asdipole Dielectric andremanent charge both
move
(d)Dipole at zero
volts again and inthe opposite
direction
(c)Dischargecapacitor
+
-
-
++
-
+
-
(A)
Q
V
(B)
Q
V
(C)
Q
V
(A)
Q
V
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Memory
The ferroelectric capacitor will give a ldquolittle bitrdquo of charge or a ldquolotrdquo of charge dependingon the direction of the applied voltage and the direction of the dipoles This property isused in modern Ferroelectric RAM ICs to make high-speed non-volatile memory chips
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9
Half Loops in a PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Switching Half Loop
Non-switching Half Loop
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Mysteries of Memory
What is this waveform It happens millions of times a second to individual databits in a magnetic disk drive when new data is written to the disk Disk drivesdepend on magnetic hysteresis to store data
-20
-10
0
10
20
30
40
50
60
70
-75 -50 -25 00 25 50 75
Packaged PZT Capacitor[ Radiant Type AB White ]
Pol
ariz
atio
n (micro
Cc
m2)
Voltage
Hint This is thestarting point
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion HysteresisElectrical hysteresis arises in natural materials much like magnetichysteresis in magnetite with which many more people are familiarMaterials engineers tinkering with composition and process have nowcreated new materials with strong ferroelectric properties and usefulness
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
A Very Short Tutorial on theOrigin of Environmental
Sensing in PZTRadiant Technologies Inc Albuquerque NM USA
radiantferrodevicescomRev B
August 27 2007
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Where do sensor properties come fromThe sensor properties arise directly from the electric dipoles in thematerial
ndash The dipoles are tied directly to the lattice and their strengths aredetermined by the lattice spacing
ndash Force and temperature change the size of the lattice
ndash Since the dipoles hold the remanent electrical charge on the plates of theferroelectric capacitor force or temperature changes applied to thecapacitor cause the dipole strength to change and force electrons to flowonto or off of the capacitor plates to keep the net electric field of thecapacitor zero
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Direct Piezoelectricity(The generation of charge due to the application of force)
The remanentdipoles exist without
an external forceapplied
An external forcestretching the latticestretches the dipolesCharge flows onto
the capacitor tocompensate
F
An external forcecompressing the
lattice shrinks thedipole Chargeflows off of the
capacitor tocompensate
F
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Pyroelectricity
The remanentdipole existswithout anexternal appliedfield
A decrease in thetemperature makes the
lattice shrink moreasymmetrically andthe dipole strength
grows Charge flowsonto the capacitor to
compensate
An increase in thetemperature makes the
lattice expandallowing more
symmetry and thedipole strength
reduces Charge flowsoff of the capacitor to
compensate
(The generation of charge due to the change in temperature)
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus either force or temperature on a ferroelectriccapacitor causes the capacitor to change the amount of charge stored on itsplates An external sensor circuit should keep track of the total charge to leaveor enter the capacitor due to a stimulus The charge integrator circuit belowperforms this function
The Charge Amp Sensor Circuit
IntegratingCapacitor (Ci)
Vout =-∆Qsensor
Ci
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
An environmental stimulus forces charge to leave the capacitor The circuit willact to keep the ldquo-rdquo node of the operational amplifier equal in voltage to the ldquo+rdquonode ie ground Thus the output voltage will change to force current to flowthrough the integrating capacitor Ci from the ldquo-rdquo node so just as much chargeleaves the ldquo-rdquo node as enters the node from the sensor capacitor The voltage onCi which is also Vout is the sum of the charge that left or entered the sensorcapacitor since the measurement began The ldquo-rdquo node always stays at zerovolts
Sensor Circuit Operation
IntegratingCapacitor (Ci)
Isensor
Vout =-∆Qsensor
Ci
Iout
SensorCapacitor (Cs)
+
-Op Amp
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative
Radiant Technologies IncRadiant EDU - A Simple Ferroelectric Tester for Education
Conclusion SensorsForce (piezoelectricity) and temperature (pyroelectricity) sensing arisedirectly from the remanent polarization of ferroelectric capacitors Thecapacitors are exquisitely sensitive and rugged Simple circuits may beused to detect changes in the capacitors originating from environmentalenvironment changes around the capacitor
Click on the link below to return to the main narrative
Return to Narrative