Raman scattering and X-ray diffraction study in Cu2GeSe3

A combined study of X-ray diffraction data and micro-Raman scattering of Cu2GeSe3 is presented. From the analysis of the X-ray data it is confirmed that this compound crystallizes in an orthorhombic cell, space group I m m 2 . From Raman spectra, optical modes are identified and their possible symmetry assignments are suggested. Peaks at 212, 266 and 300 cm−1, tentatively assigned to B2 modes, agree well with those reported from infrared reflectivity. The most strong peak at 189 cm−1 which is only Raman active is assigned to one of the two A2 modes. Lines at 135, 235 and 254 cm−1 are attributed to A1 or B1 modes. The highest phonon frequency band, observed at 385 cm−1, probably comprises the remaining A2 mode and an overtone from the strong line at 189 cm−1.