抄録
Growing process of GASH crystal was observed. If a droplet of saturated GASH solution on a slide glass is heated from upper side, platelets obtained afloat on the drop show six-rayed-star-shaped terraces. The mechanism of terrace formation is ascribed to bunching of progressing atomic steps. On the other hand, if heated from lower side, some platelets obtained at the bottom of the droplet are large and thick, which show dislocation etch pits on etching, while some remain small and thin showing no pits on etching. It appears that the growing process is not diffusion. controlled but follows the screw dislocation mechanism.
Dissolution process of GASH crystal was observed. Dissolution takes place by progression of macroscopic steps, which are nucleated book at crystal edges and at dislocation emergence points. The kinetics is controlled by diffusion and macroscopic steps are understood as bunching of atomic steps.
