Model research of phonon spectra of argyrodites family

Abstract

Cu6PS5Br compound belongs to the large family of complex chalcohalides crystallizing in the argyrodite structures. The main peculiarity of the copper-containing argyrodites is high ionic conductivity of Cu+ions, which makes it possible to use as the functional electronic materials. In the present study, the crystal structure of Cu6PS5Br argyrodite have been analyzed and described using the superspace symmetry concept. The program operating under the Maple environment and suitable for theoretically calculating the phonon spectra of the Cu6PS5Br argyrodite crystal has been developed. Zone structures have been calculated and presented for a series of model Сu6PS5Br phases. The eigenvalues of the generalized dynamic matrix have been found as well as the dispersion dependences have been built for the directions ?–X–M–R–?–M of the Brillouin zone.