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Interpretation Of Anomalies In The Raman Spectrum Of K2Seo4 In Terms Of Oxygen Sublattice Disorder, Nestor Massa, Frank Ullman, John R. Hardy

John R. Hardy Papers

Raman scattering from K₂SeO₄ crystals has been studied in the (20-800)-K temperature range. Three portions of the spectrum are discussed: defect-induced scattering, primarily below 100 cm^-1, the external mode spectrum below 200 cm^-1, and the internal mode spectra in two regions, 300-500 and 800-950 cm^-1. The temperature dependence of the low-frequency, defect-induced scattering has been correlated (in previous studies) with the temperature dependence of certain nonzero-wave-vector phonons that have been observed by others using inelastic neutron scattering. Close to the incommensurate transition temperature, T_i= 129 K, a large enhancement …