Investigations on Cuprous Sulfide

Abstract

The activity of copper in cuprous sulfide as a function of the copper-to-sulfur ratio has been determined with the help of coulometric titrations. The homogeneity range of cuprous sulfide at 400°C extends from a copper-to-sulfur ratio of 1.9996±0.0002 for samples coexisting with metallic copper to a ratio of less then 1.93 for samples coexisting with digenite (Cu1.8S). The ratio of the effective mass of electron holes to that of the free electron has been found to be 7±2 at 435°C. Preliminary conductivity measurements suggest a considerable increase of the mobility of electron holes with an increasing copper deficit of the samples presumably due to fewer collisions of electron holes with excess electrons.