course outline chem 6182 - school of chemistry and...
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Solid State ChemistryCHEM 6182
A. P. WilkinsonSchool of Chemistry and Biochemistry
Georgia Institute of TechnologyAtlanta, Ga 30332-0400
Course outline� An overview of the synthesis and
applications of inorganic materials� Structure and compound identification in
the solid state� Electrical and ionic conductivity� Zeolites as selective catalysts, sorbents and
ion exchangers
Objectives� To provide an introduction to the concepts
underlying solid state chemistry� To illustrate the wide range of materials and
physical properties that currently available
Why Solid State Chemistry?� Many aspects of modern life are dependent
upon the availability of functional solids� Chemists are in a strong position to contribute
to their syntheses – However, the chemist needs to be able to
understand what they are trying to make and why
Properties of interest� Optical
– Non-linear optics, lasers, phosphors etc..� Electrical
– Conductivity and response to stimuli� Magnetic
– Data storage, electromechanical devices� Structural� Catalytic� Etc.
Optical properties� Non-linear optical materials play an
important role in data transmission and storage– LiNbO3, KTiOPO4,KH2PO4
� Laser materials– semiconductors and laser host crystals
� Phosphors– for displays and imaging
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NLO Materials and Second Harmonic Generation
� NLO materials can be used to double the frequency of laser radiation- Useful as short wavelength
lasers can be difficult to make
� Short wavelength radiation better for information storage and transmission
Semiconductor blue lasers
Color centers� Exposure to radiation can induce defects
– Useful for imaging– Useful for dating
KBr KCl NaCl
Electrical properties� Useful electrical properties include
– superconductivity– semiconductors– ceramic metals for electrodes– response to stimuli e.g. heat and pressure– dielectric properties– ionic conductivity for electrochemical cells– conversion of heat or light to electrical power
� Interesting properties include– low dimensional behavior
K2[Pt(CN)4]Br0.3.3H2O� Is a one dimensional metal
– has a high conductivity in one direction only– when viewed under polarized light it looks
metallic for one polarization and transparent for another
– why ?
K2[Pt(CN)4]Br0.3.3H2O viewed with transmitted polarized light
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K2[Pt(CN)4]Br0.3.3H2O viewed with polarized reflected light
The packing of Pt(CN)4 units in K2[Pt(CN)4]Br0.3.3H2O
From Peters et al. Inorg. Chem. 15, 782 (1976).
Superconductors� Many materials are superconducting
– however, until 1986 all superconductors had critical temperatures < 30 K
� Superconductors find application in magnet construction
� High Tc superconductors are just starting to be used– initially in MRI and cell phone base stations
Levitating a magnet over YBCO
The structure of YBa2Cu3O7 Superconducting detector for MRI
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Semiconductors� Methods such as Chemical Vapor
Deposition are of great importance in the semiconductor industry
� Chemists play a vital role in the development of compounds that can be used in CVD
Ionic conductivity� Solids that are capable of conducting ions
are used in the fabrication of electrochemical cells– oxygen sensors in automobiles– electrolytes in fuel cells– electrolytes in high energy density batteries
Magnetic materials� Data storage� Transformers and motors� Data read out
– state of the art disk drives employ Magneto Resistive materials in the drive heads
� Shaft seals– ferrofluids can be confined in the area to be
sealed using magnetic fields
Ferrofluids
Ferroelectric materials� Crystals can have electric dipole moments just like
molecules� If the direction of the dipole moment can be flipped by
an applied field the material is said to be ferroelectric
Shape selective catalysts� Zeolites offer a way of carrying out
chemistry in very confined spaces� The type of chemistry that can be done is
determined by the pore sizes that can be made– entirely reliant upon a chemists skills
� Great industrial importance– gasoline cracking
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Ion exchangers� Zeolites and related solids can be used as
convenient ion exchangers� Zeolite A is used as a water softener in all
powder laundry detergents in the U.S.� Zeolites are used for radioactive waste
clean up
Zeolite A
Zeolite L and Offretite Inorganic materials synthesis
� Very different from molecular synthesis– Usually can not purify solid product– Synthetic techniques are different
» high temperature preps» ion exchange reactions» intercalation / insertion processes» vapor transport» sol-gel» Chemical Vapor Deposition (CVD)