Systematic hardness measurements on mixed and doped crystals or rubidium halides

Abstract

Efforts are made to improve the hardness of rubidium halide crystals by (i) solid solution hardening and (ii) impurity hardening. Systematic microhardness measurements have been made on rubidium halide mixed crystals (RbBr-RbI and KI-RbI) and rubidium halide crystals doped with Sr2+ ions. The composition dependence of the hardness of mixed crystals follows the law ΔHv = K x (1-x), where ΔHv is the enhancement in hardness, K a constant and x and (1 - x) the concentrations of the first and second component of the mixed crystals, respectively. The hardness of doped crystals increases with the concentration C of the dopant according to the law, ΔHv = k Cm, where k and m are constants. The relative efficacy of the two methods of hardening is discussed.