Raman spectroscopic studies on decomposition of spinel-type cobalt chromium indium sulfide solid solutions22

Raman spectra of spinel-type cobalt chromium indium sulfide solid solutions are presented in order to establish the decomposition of these solid solutions to chromium-rich and indium-rich sulfides on annealing at 873 and 1073 K. The results suggest that in the case of the undecomposed solid solutions there is a random distribution of the trivalent metal ions even in a vibrational spectroscopic size-scale. In the case of the at ambient temperature metastable solid solutions, the three F2g modes display two-mode behavior, whereas the A1g and Eg modes exhibit one-mode behavior. The phonon mode of species Eg of inverse spinel-type CoIn2S4 is reassigned to being close to 250 cm−1 instead of 180 cm−1 as established by Raman single-crystal experiments.