Post on 21-Aug-2020
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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
Microscopy Techniques
• SEM – Scanning Electron Microscopy
• What information can I get from it?
• Surface morphology
• Resolution of ~1nm in the best cases
• 3D reconstructions of the sample
Microscopy Techniques
• STEM – Scanning Transmission Electron Microscopy
• What information can I get from it?
• Z-contrast imaging (transmission imaging with enormous contrast)
• Morphology
• Less electron beam damage of the samples than TEM in similar conditions
• Resolution of ~1nm
Microscopy Techniques
• STEM – Scanning Transmission Electron Microscopy
• What information can I get from it?
• Z-contrast imaging (transmission imaging with enormous contrast)
• Morphology
• Less electron beam damage of the samples than TEM in similar conditions
• Resolution of ~1nm
Microscopy Techniques
• HRTEM – High-Resolution Transmission Electron Microscopy
• What information can I get from it?
• Local determination of the crystal structure
• Evaluation of the crystallinity, strain, grain boundaries, and disorder at interfaces
Microscopy Techniques
• SAED – Selected Area Electron Diffraction
• What information can I get from it?
• 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)
Microscopy Techniques
• EDX – Energy Dispersive X-Ray Spectroscopy
• What information can I get from it?
• 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
Microscopy Techniques
• AFM – Atomic Force Microscopy
• What information can I get from it?
• Surface topology
• Surface roughness
• Surface properties (few nm2) including: mechanical behavior, chemical forces, surface chemistry, magnetic field, and electric field or charge
Microscopy Techniques
• STM – Scanning Tunneling Microscopy
• What information can I get from it?
• Local energy-level structure
• Electronic bandgaps
• Surface topography
• Atomic- and molecular-resolution images
• Electrical conductance maps
Microscopy Techniques
• Profilometry
• What information can I get from it?
• Quick measurement of thickness
profile of a hard material on a
substrate
Microscopy Techniques
• Optical Microscopy
• What information can I get from it?
• Morphology
• Resolution of ~200 nm
Microscopy Techniques
• Confocal Microscopy
• What information can I get from it?
• Morphology in 3D in solution in real
time
• Resolution of ~200 nm
Microscopy Techniques
• Polarized Optical Microscopy
• What information can I get from it?
• 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
• What information can I get from it?
• 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
Diffraction Techniques
• Neutron Diffraction
• What information can I get from it?
• Crystal structure information
including hydrogen atom locations
• Structure of magnetic lattice
Diffraction Techniques
• SAXRD – Small-Angle XRD
• What information can I get from it?
• 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
• What information can I get from it?
• Very similar to SAXRD but works better on certain samples, like liquids
Spectroscopic Techniques
• EXAFS – Extended X-Ray Absorption Fine Structure
• What information can I get from it?
• 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
Spectroscopic Techniques
• XPS – X-Ray Photoelectron Spectroscopy
• What information can I get from it?
• 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
Spectroscopic Techniques
• MS – Mass Spectrometry
• What information can I get from it?
• 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
• What information can I get from it?
• Spatially resolved (~ 10 nm) surface composition
Spectroscopic Techniques
• NMR – Nuclear Magnetic Resonance
• What information can I get from it?
• 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
Spectroscopic Techniques
• EPR – Electron Paramagnetic Resonance
• What information can I get from it?
• 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
Spectroscopic Techniques
• Mössbauer Spectroscopy
• What information can I get from it?
• 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
Spectroscopic Techniques
• ICP-AES – Inductively Coupled Plasma Atomic Emission Spectroscopy
• What information can I get from it?
•
• Determines extremely accurately the atomic composition of a solid or solution for a nearly arbitrary number of elements
• Often coupled to MS
Spectroscopic Techniques
• UV-VIS-NIR – Ultraviolet Visible Near Infrared Spectroscopy
• What information can I get from it?
• Optical absorbance of molecules in solution or solids
• Extinction coefficients
• Concentrations of molecules
• Thickness of solids
• Local symmetry detail
• Electronic transition assignments
Spectroscopic Techniques
• RAMAN Spectroscopy
• What information can I get from it?
• Particle size in nanocrystalline materials
• Identification of crystal phases locally
• Local symmetry detail
• Determination of force fields
• Qualitative bond strength information
• Assignments of lattice vibrations
Spectroscopic Techniques
• SERS – Surface-Enhanced Raman Spectroscopy
• What information can I get from it?
• 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
Spectroscopic Techniques
• FTIR – Fourier-Transform Infrared Spectroscopy
• What information can I get from it?
• Quantitative identification of functional groups in liquids or solids
• Allows identification of whole molecules via the fingerprint modes
• Local symmetry detail
• Determination of force fields
• Qualitative bond strength information
• Assignments of lattice vibrations
Spectroscopic Techniques
• Ellipsometry
• What information can I get from it?
• Refractive index of a thin film
• Absorptivity of a thin film
• Thickness of a thin film
• Anisotropicity of a thin film
Magnetic Techniques
• Magnetometry
• What information can I get from it?
• 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
• What information can I get from it?
• 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
• What information can I get from it?
• 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
• What information can I get from it?
• 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
• What information can I get from it?
• Temperature and kind of phase transitions in the system
• Decomposition temperatures
• Thermodynamics of reaction
Adsorption Techniques
• Gas Adsorption
• What information can I get from it?
• 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
• What information can I get from it?
• Surface charge on colloidal
substances