Raman Spectroscopic Study of the Rare Earth Sesquisulfides
PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
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The sesquisulfides of the rare earths exists in six different crystallographic forms depending on temperature of synthesis and ionic radius of the rare earth. The structures and crystal chemistry have been studied intensively. Because of the range of crystal structures and coordination polyhedra of the rare earth ions, it is of interests to examine the vibrational spectra of these compounds. The spectra may then be compared with the vibrational spectra of related ternary rare earth-containing sulfide structures. Raman spectra have been measured on carefully synthesized and characterized sesquisulfides of the rare earth ions plus yttrium and scandium. Six structure types are represented. The Raman spectra are diagnostic of the structures type. Raman line widths indicate structural disorder only in the defect gamma type structure. High wavenumber bands shift with ionic radius of the rare earths and only slightly with cation coordination number.
- Physical Chemistry