Microhardness of single-crystal samples of Ag7+x(P1–xGex)S6 solid solutions

This work presents the results of microhardness investigations of single-crystal samples of Ag7+x(P1–xGex)S6 (x = 0, 0.1, 0.25, 0.33, 0.5, 0.75, 1) solid solutions. The dependences of microhardness H on load P and sample composition were investigated. The microhardness was found to decrease with applied load, which indicates presence of “normal” indentation size effect in Ag7+x(P1–xGex)S6 solid solutions. The obtained results were approximated in the framework of the geometrically necessary dislocations (Nix–Gao) model, and the model parameters were found. The effect of heterovalent Р5+ → Ge4+ substitution on the mechanical properties of Ag7+x(P1–xGex)S6 crystals was determined.