DEVELOPMENT OF POTASSIUM SODIUM NIOBATE FILLED POLYACRYLONITRILE (PAN) MATRIX

COMPOSITE USED FOR PIEZOELECTRIC APPLICATIONS

Presented by

Rohan R. Parsewar (MIS No. 111111038) Hanmant A. Gawade (MIS No.141211005)

Introduction

Objective

Literature Survey

Experimental Work

Future Plan

Conclusion

CONTENT

Piezoelectric are a class of materials that can transfer mechanical energy into electrical and vice versa

Ceramics like PZT have excellent dielectric properties but their use is restricted

Some of the polymers show dielectric properties but their use is restricted

INTRODUCTION

Intense work has been done on development of ceramic filled polymer matrix composite

PVDF polymer has received largest attention

However there is a need to find substitute for PVDF due to its toxic effects on environment

To find a suitable substitute for PVDF and PZT composites.

Substitute is expected to give comparable piezoelectric and dielectric properties.

Substitute has no or lesser hazardous effects on environment and health.

Objective

LITERATURE SURVEY

Dielectric constant increases as volume fraction of filler increases

Higher temperature stability can be achieved by using modified ceramic filler

Polyvinylidene fluoride-modified BaTiO3 composite

Fig 1 Density and relative density of PVDF BTO composite as a function of volume fraction of BTO.

Fig.2 Dielectric loss and dielectric constant at 1 KHz as a function of temperature.

Highly aligned whiskers of BatiO3 are added instead of its powder

All dielectric parameters like dielectric constant remanant polarization are high in whisker form than in powder form

PVDF Matrix Composite Containing BatiO3 Whiskers

Fig 3 Ferroelectric hysteresis loops for 30% whisker-PVDF composite: (a) normal and (b) parallel specimens

Fig 4 Profiles of: (a) powder-PVDF composite (b) parallel specimen and (c) normal specimen.

Here main focus is to tailor

Curie temperature

Particle size

Volume fraction.

Preparation of PLZT/PVDF composite

Fig 5 Effect of La content (x) on Curie temperature of Pb1−x Lax(Zr0.55Ti0.45)1−x/4O3ceramics.

Effects of ceramic volume fraction and particle size on (a) piezoelectric coefficient and (b) dielectric constant of a) PL0.04ZT/PVDF, (b) PL0.07ZT/PVDF composites.

Not only as a product Halogen based polymers have serious environmental issues during their synthesis as well

Apart from PZT and Barium Titanate deserving attention was not given to the any other ceramic

Considering strict environmental regulations need to find substitution for PVDF is inevitable which should be halogen free

NEED TO SUBSTITUE PVDF

Low density-1.15 g.cm−3

Thermal stability

High strength

Shows a dielectric constant in the range 4.5-5.5

Polyacrylonitrile (PAN)

Potassium Sodium Niobate (KNN)

The crystal structure of KNN

Potassium Sodium Niobate (KNN) is lead-free ceramic

Piezoelectric d33coefficient typically between 80 and110 pC/N

Dielectric constant is 200-250

Potassium Sodium Niobate (KNN)

Lead free ceramic

Non toxic

Sodium and potassium carbonates are readily available

Good dielectric and piezoelectric properties

WHY KNN

EXPERIMENTAL WORK

XRD of K2CO3

Angle 2 theta

Inte

nsity

Anode material- Cu

K-Alpha 1 wavelength – 1.540598

K-Alpha 2 wavelength - 1.544426

Ratio K1/K2 - 0.5

Generator Voltage- 40 V

Tube Current – 30

XRD of K2CO3

XRD of Na2CO3

 

Angle 2 theta

Inte

nsity

Anode material- Cu

K-Alpha 1 wavelength – 1.540598

K-Alpha 2 wavelength - 1.544426

Ratio K1/K2 - 0.5

Generator Voltage- 40 V

Tube Current – 30

XRD of Na2CO3

BET is Brunauer Emmett Teller method determine the total specific surface area in m2/g

Uses concept of adsorption of gas molecules on a solid surface

Based on the amount of gas absorbed at a given pressure, the BET equation is used to calculate the number of adsorbed gas molecules that would be required to form a mono layer on the surface.

With knowledge of the cross section area of the gas

molecules adsorbed, the surface area can be easily calculated.

BET analyisys of K2CO3 and Na2CO3

SR NO Component Weight of empty tube (gm)

Weight with component (gm)

1 K2CO3 24.6005 26.5864

2 Na2CO3 24.2540 26.2264

Calculations & Result

Surface Area of Na2CO3= 3.01 m2/g.

Surface Area of K2CO3= 3.54 m2/g

FUTURE PLAN

(Na2CO3) and (K2CO3) heated at 2000 C for 2 hours to remove moisture.

Milling is done in jar mill for 3-4 hours of mixture of (Na2CO3), (K2CO3) and (Nb2O5).

Calcinations of above mixture at 8500 C- 9500 C for 4 hours in F/C

Fabrication of KNN

REACTION: 1(Na2CO3) +1(K2CO3) +2 (Nb2O5) 4 [( K.5 Na.5)NbO3] +2(CO2)

Now 1 mole of [(K.5 Na.5)NbO3] = 172 gram

By above reaction balancing we note that to produce 1 mole of KNN we require 0.25 moles each

of (Na2CO3) and (K2CO3) and .5 mole of (Nb2O5)

0.25 mole of (Na2CO3) =26.5 g

0.25 mole of ( K2CO3) =34.5g

0.5 mole of ( Nb2O5) =133g

Numerical Calculations For Fabrication of KNN

Sr No.

Component Molecular Weight

1 Sodium Carbonate (Na2CO3) 106

2 Potassium Carbonate ( K2CO3) 138

3 Niobium Pentoxide ( Nb2O5) 266

4 Potassium Sodium Niobate[( K.5 Na.5)NbO3] 172

5 Carbon Dioxide(CO2) 44

i.e 25/172=0 .1453 mole Mole of (Na2CO3) = .1453/4 = 0.0363 mole = 3.8478g

… … I

Mole of ( K2CO3) = .1453/4 =0 .0363 mole = 5.0094g … … … II

Mole of ( Nb2O5) = .1453/2 = 0.07265 mole =19.3249g … … … III

  Amount of CO2 evolved = (I+II+III)- 25g of KNN=28.1821-

25= 3.1821g=0.0723 mole

To produce 25 g of KNN

X-Ray Diffraction (XRD)

A Scanning Electron Microscope (SEM)

Characterization for KNN:

It can be processed by processing techniques like:-

Hot Pressing

Compression Moulding

Film Casting

Composite Synthesis Process

Thermo gravimetric analysis (TGA)

X-ray diffraction (XRD)

Scanning electron microscope (SEM)

BET for surface area analysis.

Impedance spectroscopy is used to dielectric properties.

Characterization Of composite :

Substitution for halogen based polymers and lead based ceramics is feasible

There are different parameters must be considered during composite fabrication

PAN matrix composite having ceramic named KNN as filler is to be fabricated

It is expected to give comparable properties with less or no hazardous effect on environment

Conclusion

[1] Fundamentals of Materials Science and Engineering - By William Callister [2] Wikipedia- free encyclopedia [3] Piezoelectric properties of cement based/PVDF/PZT

composites [4] Preparation and properties of polymer matrix piezoelectric

composites containing aligned BaTiO3 whiskers. [5] Highly enhanced piezoelectric properties of PLZT/PVDF

composite by tailoring the ceramic Curie temperature, particle size and volume fraction.

[6] Microstructural, structural, dielectric and piezoelectric properties of potassium sodium niobate thick films.

 

REFERENCE