Anomalies of properties in a series of K2Co x Ni1-x (SO4)2 • 6H2O mixed crystals

The microhardness and thermal stability of K2Co (x) Ni-1- (x) (SO4)(2) center dot 6H(2)O mixed crystals have been investigated. Microhardness peaks and dehydration onset temperatures are found in the composition range x = 0.05-0.23. The observed anomalies of properties are related to the anomalous changes in the structural parameters of the crystals in this composition range with an increase in the cobalt content. It is shown that structural imperfection of the crystals depends on the sectorial inhomogeneity and reaches a maximum at x = 0.43-0.54.