Vickers microhardness studies of l-arginine halide mixed crystals

Vickers microhardness of mixed crystals of l-arginine hydrochloride monohydrate (LAHCl) and l-arginine hydrobromide monohydrate (LAHBr) has been measured on the (100) cleavage plane for various compositions and correlated with dislocation density. Both the Vickers microhardness and dislocation density of as grown crystals are found to be maximum at intermediate compositions. Dislocations originating from internal strain are found to be the prime factors for the observed hardening. The microhardness behavior of this mixed system is explained successfully with the help of the PSR model proposed by Li and Bradt.