T-x diagram and transport properties of the GeSe-GeI2 solid electrolyte

Abstract

The T-x diagram for the GeSe-GeI2 system was plotted based on DTA, XRD, and conductivity data. The diagram features a simple eutectic and a limited region of solid solutions with prevalent GeSe content. It was established that, in the region of solid solutions, the properties of the GeSe-GeI2 solid electrolyte are substantially dependent on the concentration of the GeI2 dopant. The highest conductivity (10−3−10−4 S/cm at 150°C), lowest activation energy of electric conduction (0.3–0.4 eV), and lowest electronic (hole) transport numbers (10−5−10−7 at 150°C) at high ionic (∼1.0) and cationic (0.9–1.0) transport numbers were observed at a GeI2 concentration of 3–6 mol %. In the two-phase region, the transport properties (conductivity and activation energy of conduction) only slightly depend on the dopant concentration.