MICROHARDNESS OF SINGLE CRYSTALS OF Ag7+x(P1-xGex)S6 SOLID SOLUTIONS

Abstract

Superionic conductors have a number of important characteristics and applications that make them important in the field of materials science, technology and industry. At the same time, when developing and analyzing the properties of new materials to optimize their composition and material processing, information about microhardness is mandatory. This is important to ensure the stability and efficiency of devices over a long period of time. This paper presents a study of the microhardness 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. For all the studied samples, a decrease in the microhardness H is observed with an increase in the load P, indicating the presence of a direct size effect. The microhardness of single-crystal samples is also described within the PSR (proportional specimen resistance) model, the results of which also indicate the presence of a direct size effect. The values of the intrinsic hardness H0 calculated within the PSR model for solid solutions of Ag7+x(P1-xGex)S6 (x = 0, 0.1, 0.25, 0.33, 0.5, 0.75, 1) are as follows: 903.1 N/mm2 (x=0), 997.7 N/mm2 (x=0.1), 990.2 N/mm2 (x=0.25), 1019.9 N/mm2 (x=0.33), 1053.3 N/mm2 (x=0.5), 1097.8 N/mm2 (x=0.75), 1081.1 N/mm2 (x=0.1). To assess the influence of the direct size effect, Meyer's law was used. For the studied solid solutions of Ag7+x(P1-xGex)S6, the values of the Meyer's index are in the range n = 1.72 ÷ 1.86, which indicates that these solid solutions belong to soft materials.