Phase transitions and transport properties of complex copper chalcogenides

Abstract

We have studied properties of a recently synthesized class of complex copper chalcogenides A-Cu-X (where A = alkali metal or alkaline earth metal and X = S, Se, Te). In this contribution we have focused on the phase transitions and transport characteristics of this family of compounds. Very interesting and noticeable features such as: phase transitions connected with CDW formation in K3Cu8S6, Rb3Cu8S6, and K3Cu8Se6, the unusual linear T behaviour of metallic resistivity down to T ≪ ΘD in K3Cu8Te6, the metal-nonmetal transition with a metallic phase at low temperatures in BaCuS3-x and KCu3Se2 have been observed. A striking correlation between the dimensionality of the crystal lattice and the temperature dependence of resistivity, found for several chalcogenides, is discussed.