Raman and infrared vibrational spectra of PbGa2S4 crystal

Abstract

Raman scattering spectra in different geometries at temperatures 10 - 300 K and infrared vibrational spectra were investigated for PbGa2Se crystals. Contours of reflection spectra were calculated and parameters of phonons and dielectric constants were determined. Temperature dependences of Raman spectra were investigated and soft modes with different temperature dependences in intervals 80 - 150 and 150 - 370 K were discovered. A group of lines attributed to Davydov multiplets was found out and their polarization dependences temperature changes were investigated. Effective ion charges were calculated and a polarizability of ionic charges of Pb, Ga and S in PbGa2S4 lattice was determined.