Surface Micromorphology of Different Crystallographic Faces of L-arginine Hydrochloride Monohydrate Etched in Organic Solvents

Abstract

The surface micromorphology of {100}, {010}, {001} and {110} faces of L-arginine hydrochloride monohydrate (LAHCl) crystals etched in various organic solvents and their mixtures with water has been studied by optical microscopy. Selective behaviour of the etchants for revealing screw and edge dislocations, etch channels, etch grooves and terraced etch pits has been demonstrated. It is observed that addition of impurity like FeCl 3 , to the etchants facilitates the formation of dislocation etch pits and is interpreted in terms of Cabrera's thermodynamic theory of dislocation etch pit formation. Crystallinity of the as grown crystals is determined from etch pits count in unit area of different faces and the average dislocation density is found to be ∼10 4 cm -2 .