Infrared and Raman study of lattice vibrations of CdAl2Se4 and CdAl2S4 single crystals

Citation
A. Eifler et al., Infrared and Raman study of lattice vibrations of CdAl2Se4 and CdAl2S4 single crystals, J PHYS-COND, 11(25), 1999, pp. 4821-4832
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS-CONDENSED MATTER
ISSN journal
0953-8984 → ACNP
Volume
11
Issue
25
Year of publication
1999
Pages
4821 - 4832
Database
ISI
SICI code
0953-8984(19990628)11:25<4821:IARSOL>2.0.ZU;2-3
Abstract
Infrared and Raman spectra of oriented CdAl2Se4 single crystals and of as-g rown CdAl2S4 single crystals have been measured in the wavenumber range fro m 600 to 25 cm(-1). Both ordered vacancy compounds grown by the chemical va pour transport method crystallize in the thiogallate structure with space g roup I (4) over bar. All 13 optical phonon modes are Raman active; ten of t hese are in addition infrared active. We report for the first time the comb ined infrared and Raman study of the optical phonon modes of both compounds . With the complementary information from infrared and Raman spectroscopy a ll optical phonon modes have been identified and assigned to their correspo nding symmetry classes. The fact that all five modes of E symmetry exhibit a counterpart of B symmetry in the close spectral environment is unambiguou s evidence of space group I (4) over bar. The measured frequencies of the n onpolar modes are in a very good agreement with data calculated in the fram ework of a simplified Keating model. For an oriented CdAl2Se4 single crysta l the directional dispersion of the polar phonons has been studied.