A study of the mechanisms of defect formation in K2Ni(SO4)2 · 6H2O/K2Co(SO4)2 · 6H2O bicrystals grown from aqueous solutions

Abstract

The K2Co(SO4)2 · 6H2O-K2Ni(SO4)2 · 6H2O system has been studied, and a series of K2Ni(SO4)2 · 6H2O/K2Co(SO4)2 · 6H2O bicrystals have been grown. The processes of defect formation at the substrate/layer interface K2Co(SO4)2 · 6H2O/K2Ni(SO4)2 · 6H2O are studied by probe microanalysis, X-ray topography, and optical microscopy. It is found that inclusions and threading dislocations are formed at the interface, due to which elastic stresses relax in the crystal. Nickel is nonuniformly distributed in the layer; its concentration decreases with an increase in the layer thickness, which is indicative of substrate dissolution in the initial stage of interaction. A way for the elastic mismatch stresses to relax in heterostructures of brittle crystals obtained from solutions at low temperatures is proposed which implies the formation of inclusions at the substrate/layer interface.