Electrical conductivity, electrochemical and optical properties of Cu7GeS5I-Cu7GeSe5I superionic solid solutions

Abstract

Single crystals of Cu₇GeS₅I–Cu₇GeSe₅I superionic solid solutions were grown by chemical transport. Their electrical conductivity in the frequency range 1.0⋅10⁶–1.2⋅10⁹ Hz and in the temperature range 100–300 K was measured; the compositional dependences of the electrical conductivity and activation energy were obtained. Electrochemical studies of Cu₇GeS₅I–Cu₇GeSe₅I solid solutions were performed, the character of compositional variation of the electrode potential and the range of the electrochemical stability at S→Se substitution were determined. The optical absorption edge of Cu₇GeS₅I–Cu₇GeSe₅I superionic solid solutions in the temperature range 77–300 K were studied; the compositional dependences of the optical pseudogap and Urbach energy were obtained.
Keywords: superionic conductors, electrical conductivity, electrochemical properties, optical absorption edge
PACS: 72.80.Jc, 78.40.Ha