Solid State Chemistry (Fall 2016) Instructor: Jihoon Choi
Solid State Chemistry
7th week
177
Solid State Chemistry (Fall 2016) Instructor: Jihoon Choi 178
1. Crystal Structures and Crystal Chemistry
2. Crystal Defects, Non-stoichiometry and Solid Solutions 3. Synthesis, Processing and Fabrication Methods
4. Characterization Technique 5. Bonding in Solids
Table of Contents
Solid State Chemistry (Fall 2016) Instructor: Jihoon Choi 179
What is it?
Solid State Chemistry (Fall 2016) Instructor: Jihoon Choi 180
Characterization Technique
* X-Ray Diffraction
λ = 2d · sinθ
Bragg Law
Solid State Chemistry (Fall 2016) Instructor: Jihoon Choi 181
* Optical and Electron Microscopy Techniques
- Optical Microscopy - Electron microscopy
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Characterization Technique
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* Spectroscopic Techniques
- works on the principle that under certain conditions, materials absorb or emit energy - usually it is electromagnetic radiation
- usually a plot of intensity of absorption or emission (y axis) as a function of energy (x axis)
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Characterization Technique
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* Spectroscopic Techniques
- Vibrational spectroscopy: IR and Raman - Visible and ultraviolet (UC) spectroscopy
- Nuclear magnetic resource (NMR) spectroscopy - X-ray spectroscopies: XRF, AEFS, EXAFS
- Electron spectroscopies: ESCA, XPS, UPS, AES, EELS
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Characterization Technique
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* Thermal Analysis (TA)
- TA involves the measurement of certain physical and chemical properties as a function of T - mainly enthalpy, heat capacity, mass and coefficient of thermal expansion
- thermogravimetry analysis (TGA)
- differential scanning calorimetry (DSC)
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Characterization Technique
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Characterization Technique
* Thermogravimetry analysis (TGA)
- Measures the change in mass of a substance as a function of temperature or time
- Under conditions of dynamic heating, decomposition usually takes place over a range of temperatures, Ti to Tf, and a second constant-mass plateau is observed above Tf, which
corresponds to the mass of the residue Mf
- Used for quantitative calculation of compositional changes
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* Stepwise decomposition of calcium oxalate hydrate by TG
Characterization Technique
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Characterization Technique
* Differential scanning calorimetry (DSC)
- The temperature of a sample is compared with that of an inert reference material during a programmed change of temperature
- The temperatures should be the same until some thermal event (e.g. melting, decomposition, change in crystal structure, etc.) occurs, in which case the sample temperature either lags behind (if the change is endothermic) or leads (if the change is exothermic) the reference temperature
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Characterization Technique
* Differential scanning calorimetry (DSC)
- insensitive to small heat effects
- with a reference sample, the sloping baseline can be removed
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* Thermal Analysis of reversible and irreversible changes
Characterization Technique
(a)dehydration
(b)polymorphic transition (c) melting/solidification
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Characterization Technique
* Phase Diagram
- DSC is a powerful method for the determination of phase diagram, especially in conjunction with other techniques such as XRD for phase identification
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