Study of Structural and Vibrational Properties of Cu2In4Se7 by Analytical Methods

The compound Cu2In4Se7 was synthesized, the crystal structure and atomic dynamics were studied. The studies were carried out at room temperature and under normal conditions using XRD, Raman spectroscopy and FTIR spectroscopy. The obtained X-ray structural spectra were analyzed by the Rietveld method and various crystallographic parameters were determined. It was established that the crystal structure of this compound corresponds to tetragonal symmetry with the space group P-42c (112). As a result of the analysis of the Raman spectrum with the Gaussian function, it was established that in the Cu2In4Se7 crystal in the frequency range ν = 0–800 cm-1 3 main vibrational modes are observed: ν1 = 146 cm-1, ν2 = 171 cm-1 and ν3 = 229 cm-1. It was found that these modes correspond to vibrations of InSe4 tetrahedra formed by In-Se bonds. As a result of analysis of the FTIR spectrum, it was established that 3 main vibration modes are observed in the Cu2In4Se7 crystal in the wavenumbers range ν = 400-4000 cm-1. These modes are associated with water and carbon dioxide molecules in the sample.