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VIBRATIONAL SPECTRA AND FORCE CONSTANTS OF SPINELS.

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Title: VIBRATIONAL SPECTRA AND FORCE CONSTANTS OF SPINELS.
Creators: DeAngelis, Bernardo A.; White, William B.
Issue Date: 1969
Abstract: The spinels are a large family of compounds of general formula $A_{2}BX_{4}$. A is octahedrally coordinated and B is tetrahedrally coordinated. The space group is Fd3m, $O^{7}_{h}$ with 14 atoms in the primitive cell. A factor group analysis of the structure yields $A_{1g}(R)+E_{g}(R)+T_{1g} (inactive)+3T_{2g}(R)+2A_{2a} (inactive)+2E_{a} (inactive)+4T_{1u}(IR)+T_{1u}(acoustic)+2T_{2u}(inactive)$. Infrared and Raman spectra have been measured on a number of III-II, II-IV and I-VI spinels. (The Roman numerals refer to the valence states of the ions on the A and B sites respectively). A normal coordinate analysis of the structure has been performed using a simplified model containing only stretching force constants for the octahedral and tetrahedral bonds. Values of the tetrahedral force constant varies from 6.35 mdyne/\AA in $Na_{2}WO_{4}$ to 0.90 in $Cr_{2}CoO_{4}$. The octahedral force constants vary from $0.26 mdyne/\AA$ to 2.01 for the same compounds.
URI: http://hdl.handle.net/1811/15808
Other Identifiers: 1969-Q-4
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