Influence of cation substitution on phase transition and optical absorption edge in Cu₆(P₁₋xAsx)S₅I mixed crystals

Abstract

Cu₆(P₁₋xAsx)S₅I mixed crystals were grown using chemical vapour transport. Temperature isoabsorption investigations of optical absorption edge enable to reveal anomalies typical for the first- and second-order phase transitions as well as to construct the x, T-diagram. The spectrometric measurements of the optical absorption edge in Cu₆(P₁₋xAsx)S₅I superionic mixed crystals were carried out within the temperature range 77-320 K. The influence of temperature and composition on optical absorption edge, parameters of exciton-phonon interaction as well as ordering-disordering processes in Cu₆(P₁₋xAsx)S₅Isuperionic mixed crystals have been studied.