OBSERVATIONS OF CLEAVAGE STEPS, SLIP TRACES AND DISLOCATION HOLLOW CORES ON CLEAVED (100)FACES OF L-ARGININE PHOSPHATE MONOHYDRATE SINGLE-CRYSTALS BY ATOMIC-FORCE MICROSCOPY

The results of an atomic force microscopy study of the nature of cleav age steps, observation of slip traces and formation of hollow cores at the centres of dislocations on the {100} faces of L-arginine phosphat e monohydrate (LAP) single crystals grown from aqueous solutions are d escribed and discussed. it was observed that: (1) most of the cleavage steps and all the slip traces are of elementary height, a=1.085 nm; ( 2) the origin of a cleavage step may or may not have a hollow core; an d (3) close to its origin, the curvature of a cleavage step may be pos itive or negative or may change from positive to negative. The results suggest that slip traces observed on the cleaved surfaces of LAP are formed during the cleavage process while the rounding and the rearrang ement of elementary cleavage steps take place immediately after the oc currence of cleavage. Analysis of the results also shows that the disl ocations responsible for the origin of hollow cores always represent a stress field state corresponding to a trapped solution of different l ocal interface supersaturations. (C) 1997 Elsevier Science B.V.