Etch Pit Studies of Stearic Acid Single Crystal

Abstract

Dislocations in stearic acid single crystal grown from a benzene solution were observed by etch pits. The correspondence of etch pits to dislocations was confirmed from the observation of pits on the matched cleavage surface, etching steps around the pit centers and etch pits nucleated by the mechanical stresses. From the change of etch pit size, etching rate was calculated to be about 2.8 µm/sec at 15°C. It depended remarkably on temperature with the activation energy of 29±3 kcal/mol. The etch pit density was of the order of 103 to 104/cm2 on the as-grown surface and of 10 to 102/cm2 on the as-cleaved surface. An apparent correspondence between the pyramidal etch pits and growth spiral centers was confirmed. The features of dislocations were discussed in relation to the growth process of the crystal.