Anisotropic growth rate of rough crystal faces

Abstract

We present a study of the growth form of 1-benzothiophene (thionapthene) crystals growing from the melt as a function of the supersaturation σ. In equilibrium and at σ only the (001) faces are flat; the side faces are rough. Between σ=0.0002 and σ=0.0015, flat side faces appear on the growth form: (110), (201¯), and (011). At σ>0.003, the growth front of the side faces becomes unstable. To our knowledge this is the first observation of a rough crystal face which becomes seemingly faceted in a supersaturated environment. An explanation of this observation is suggested in terms of activity to growth of different sites on the rough crystal face.