elements of materials€¦ · include microscopy, diffraction, spectroscopy, thermal, adsorption,...

$: Elements of Materials€¦ · include microscopy, diffraction, spectroscopy, thermal, adsorption, mechanical, electrical, optical, and analytical techniques. •All of these techniques$
Elements of Materials

Geoffrey A. Ozin

Think About the World Around Us

• Air we breath

• Water we drink

• Gaseous and liquid fossil fuels we burn

• Rest are solids – soft and hard – amorphous and crystalline

• Molecular solids, polymers, ceramics, semiconductors, metals, superconductors and hybrid materials

• Science of materials is the science of solids

What Holds Solids Together ?

Ionic bonding

Covalent bonding

Coordinate bonding

Hydrogen bonding

Polarization forces

Van der Waals forces

Metallic bonding

Seven Materials Concepts

synthesis

structure

form

property defects

function

utility

Thinking

Materials

Key Developments Enabling Materials Chemistry

Utility of solids in advanced technologies

Type and function of defects in solids

Electronic properties of solids

X-ray structure

of solids

Solid state materials synthesis

Where do Materials Come From ?

• Petroleum

• Molecular solids

• Polymers

• Minerals

• Ceramics

• Semiconductors

• Metals and alloys

• Superconductors

Some Advanced Technology Uses of Materials

Electrical Photonic Medical Mechanical

Energy storage Displays Diagnostics Strength

Energy generation Smart windows Therapeutics Temperature stability

Information technology

Optical telecomm Imaging Weight

Chemical sensors Light sources Regeneration Abrasion

Superconductor transmission , devices

Information storage

Biochemical sensors

Vibration

Materials Food Chain

Materials

precursors

Materials

chemistry

Materials to

engineering

and medical

applications

Materials

scale –up and

manufacturing

Synthesis,

structure,

reactivity

Synthesis,

structure,

characterization

Structure

property

function

relations

Multi

disciplinary

materials science

and engineering,

biology and

engineering

collaborations

Utility – Molecules and Materials

Molecules Materials

Pharmaceuticals Films, crystals

Additives Porous materials, membranes

Dyes Thermoelectrics

Detergents Ferromagnetics, ferroelectrics

Hydrocarbon fuels Ionics, Electronics

Insecticides Photonic crystals

Chemical warfare agents Linear and nonlinear optics

Liquid crystals Imaging, lithographics

Molecular metals Piezoelectrics

Phosphors Biomedicals

Chemistry Cycle for Asking How to

Create Novel Materials and Processes

Synthetic strategies for

making a material

Molecular and materials structure

Synthetic control of

material size and shape

Relation of materials structure

and defects to properties

Relation of properties to

function

Potential uses for a material based on its function

Discovery of Molecules and Materials

Driver of Materials Science, Engineering, Biology and Medicine

Chemistry design, synthesis, structure determination, properties identification of new materials

Materials science and engineering

Biology and medicine

Materials Relations to the Real World

• National and international politics

• Public policy and priorities

• Manufacturing and business

• Science policy and priorities

Synthesis Structure and form

Properties and

function Utility

Materials Chemistry Diagnostics

• In the next few slides you will find an outline of the major characterization techniques available to a materials chemist.

• These can be categorized into “groups” that include microscopy, diffraction, spectroscopy, thermal, adsorption, mechanical, electrical, optical, and analytical techniques.

• All of these techniques are available to pretty well every university and they provide a wide spectrum of possibilities in terms of chemical, structural, morphological, and physical characterization.

Materials Chemistry Diagnostics

• You will not find any detail here but just useful guidelines as to where to look and what to look for if you need a certain kind of information about your material at different length scales.

• You can then look into each of those techniques, learn it and become an expert in it, or you can even develop your own technique. Many people did the latter in order to measure something that was not measurable at their time and many of those got Nobel Prizes for their work.

• Discovering techniques and how they work and what information they can yield is a beautiful way to see pure human ingenuity at work.

Microscopy Techniques

• TEM – Transmission Electron Microscopy

• What information can I get from it?

• Morphology, through the thickness of the sample

• Electron density distributions

• Lattice defects in crystals (like twins, stacking faults, or dislocations)

• Resolution of ~1nm


• SEM – Scanning Electron Microscopy


• Surface morphology

• Resolution of ~1nm in the best cases

• 3D reconstructions of the sample


• STEM – Scanning Transmission Electron Microscopy


• Z-contrast imaging (transmission imaging with enormous contrast)

• Morphology

• Less electron beam damage of the samples than TEM in similar conditions

• Resolution of ~1nm


• HRTEM – High-Resolution Transmission Electron Microscopy


• Local determination of the crystal structure

• Evaluation of the crystallinity, strain, grain boundaries, and disorder at interfaces


• SAED – Selected Area Electron Diffraction


• Local determination of the crystal structure

• Evaluation of the crystallinity, strain, grain boundaries, and disorder at interfaces

• (Can be performed using TEM and certain STEM)


• EDX – Energy Dispersive X-Ray Spectroscopy


• Spatial mapping of atomic composition within a sample (down to a few tens of nanometers from the surface)

• Resolution limited by the electron microscope it is attached to


• AFM – Atomic Force Microscopy


• Surface topology

• Surface roughness

• Surface properties (few nm2) including: mechanical behavior, chemical forces, surface chemistry, magnetic field, and electric field or charge


• STM – Scanning Tunneling Microscopy


• Local energy-level structure

• Electronic bandgaps

• Surface topography

• Atomic- and molecular-resolution images

• Electrical conductance maps


• Profilometry


• Quick measurement of thickness

profile of a hard material on a

substrate


• Optical Microscopy


• Morphology

• Resolution of ~200 nm


• Confocal Microscopy


• Morphology in 3D in solution in real

time

• Resolution of ~200 nm


• Polarized Optical Microscopy


• Evaluate optical activity (ability to turn the electromagnetic field) of a material often related with nanoscale ordering

• Evaluate specific ordering of a material at the nanoscale if it induces optical activity

• Structural information from optical birefringence of crystals or liquid crystals

Diffraction Techniques

• XRD – X-Ray Diffraction


• Determination of the crystal structure of a single crystal or a powder

• Evaluation of strain

• Evaluation of lattice vibrations

• Evaluation of crystal size

• Evaluation of crystal orientation

• Identification of crystalline phases

• Density of a solid material


• Neutron Diffraction


• Crystal structure information

including hydrogen atom locations

• Structure of magnetic lattice


• SAXRD – Small-Angle XRD


• Evaluation of periodicity and symmetry at the nanoscale (10 nm – 1 μm) in a sample

• Evaluation of shape, size, and separation of nanoscale objects in an ensemble

• SAXS – Small-Angle X-Ray Scattering


• Very similar to SAXRD but works better on certain samples, like liquids

Spectroscopic Techniques

• EXAFS – Extended X-Ray Absorption Fine Structure


• Provides invaluable information about the local chemical environment of specific atoms in solids, especially bond lengths, and coordination numbers and geometries

• Invaluable for glasses, particularly the first coordination sphere


• XPS – X-Ray Photoelectron Spectroscopy


• Reasonably accurate chemical composition of surfaces (error ~1–5%)

• Estimation of chemical composition as a function of depth

• For each atom identified it allows one to know the chemical environment and oxidation state

• Invaluable for glasses


• MS – Mass Spectrometry


• Molecular mass of a molecular (or cluster) species in a sample

• Identification of multiple species in a complex mixture by their molecular mass

• Determination of purity of a sample

• SIMS – Secondary-Ion Mass Spectroscopy


• Spatially resolved (~ 10 nm) surface composition


• NMR – Nuclear Magnetic Resonance


• Identification of molecular structures in solutions or solids

• Allows one to track several individual NMR active atoms (like H, C, F, N, Si, P)

• Allows one to evaluate the local environment and bonding of each atom (C atoms in different environments will give different signals in 13C NMR)

• Enables bond length determination

• Allows one to evaluate diffusion coefficients and dynamics of molecular species


• EPR – Electron Paramagnetic Resonance


• Study of molecules and solids with unpaired electrons

• Detection of organic free radicals, paramagnetic coordination

• compounds, metallic clusters with conduction electrons, doped

• conjugated polymers, and trapped electrons in solids

• Provides distribution of unpaired spin density in molecules and materials

• Defines symmetry of orbital containing unpaired electrons

• Establishes coordination geometry and number


• Mössbauer Spectroscopy


• Provides oxidation states of Mossbauer active metals like Fe, Sn, I, Au, Sb, and Eu

• Probes metal coordination geometry and coordination number

• Defines local magnetic fields


• ICP-AES – Inductively Coupled Plasma Atomic Emission Spectroscopy


•

• Determines extremely accurately the atomic composition of a solid or solution for a nearly arbitrary number of elements

• Often coupled to MS


• UV-VIS-NIR – Ultraviolet Visible Near Infrared Spectroscopy


• Optical absorbance of molecules in solution or solids

• Extinction coefficients

• Concentrations of molecules

• Thickness of solids

• Local symmetry detail

• Electronic transition assignments


• RAMAN Spectroscopy


• Particle size in nanocrystalline materials

• Identification of crystal phases locally


• Determination of force fields

• Qualitative bond strength information

• Assignments of lattice vibrations


• SERS – Surface-Enhanced Raman Spectroscopy


• Molecules and materials in close proximity to silver clusters or rough silver surfaces

• Surface plasmon electric field enhanced intensities of Raman vibrational modes

• High sensitivity probe moving towards single molecule detection


• FTIR – Fourier-Transform Infrared Spectroscopy


• Quantitative identification of functional groups in liquids or solids

• Allows identification of whole molecules via the fingerprint modes


• Determination of force fields

• Qualitative bond strength information

• Assignments of lattice vibrations


• Ellipsometry


• Refractive index of a thin film

• Absorptivity of a thin film

• Thickness of a thin film

• Anisotropicity of a thin film

Magnetic Techniques

• Magnetometry


• Defines type of magnetism of molecules and materials, including diamagnetism, paramagnetism, superparamagnetism, ferromagnetism, ferrimagnetism, and antiferromagnetism

• Electronic ground state information

• Metal–superconductivity transitions

Separation Techniques

• GC – Gas Chromatography


• Allows one to separate individual gases

from a mixture

• Often coupled to MS to obtain separation

and identification simultaneously

Separation Techniques

• GPC – Gel Permeation Chromatography

• Gradient Ultra-centrigugation


• Allows one to separate individual materials like different diameter and chirality carbon nanotubes, different molecular weight polymers and particle dispersions of capped nanocrystals based on size and shape

Thermal Techniques

• TGA – ThermoGravimetric Analysis


• Thermal stability of a compound

• Boiling point

• Decomposition temperatures

• Kinetics of solid-state decompositions

• Coupled with MS provides off-gas analysis

Thermal Techniques

• DSC – Differential Scanning Calorimetry


• Temperature and kind of phase transitions in the system

• Decomposition temperatures

• Thermodynamics of reaction

Adsorption Techniques

• Gas Adsorption


• Accessible surface area for powder sample

• Pore size

• Pore shape

• Elasticity of the material

• Adsorption and desorption kinetics

Electrical Techniques

• What information can I get from them?

• Electrical conductivity of molecules and materials

• Defines electronic properties: insulator, semiconductor, metal, semimetal, and superconductor

• Temperature dependence of conductivity establishes mechanism of charge transport

• Probes nature, population and effects of dopants, defects, and impurities

• Seebeck and Hall measurements define whether transport is by electron or hole carriers

Electrical Techniques

• Zeta Potential


• Surface charge on colloidal

substances

elements of materials€¦ · include microscopy, diffraction, spectroscopy, thermal, adsorption,...

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