FORMATION OF HOLLOW CAVITIES ON {100} FACES OF LAP CRYSTALS INVESTIGATED BY AFM

Atomic force microscopy (AFM) has been used to study the hollow cavity formation mechanisms of the L-arginine phosphate monohydrate (LAP) crystals. Hollow cavities are formed through three modes. During 2D nucleation growth, initially formed 2D cavity prevents the growth around it layer-by-layer and causes the formation of 3D cavity with stepped-walls inside. Interaction of the steps advancing along different directions generated by different dislocation sources is also responsible for the appearance of hollow cavities. When the steps overrun impurities incorporated into the kinks, triangular pits among regular elementary steps come into being.