1994 Volume 11 Issue 2 Pages 58-
Growth and dissolution of a Cdli2 crystal were investigated under microgravity by means of high resolution in situ observation using commonpath interferometry and modulation microscopy, which were employed for the observation of the concentration field and of the crystal surface, respectively. The microgravity was obtained for 6 minutes in the TR-lA rocket, which was flown from Tanegashima Island on September 16, 1991. Although the original scientific objective could not be fulfilled completely because of an accidentally introduced small gas bubble near the seed crystal, the development of Marangoni convection followed by the instability of the convection during dissolution and growth of the seed crystal was, for the first time, clearly observed. The development and the initiation of the instability of the Marangoni convection was respectively interpreted due to the coupling effects of the temperature gradient and the concentration gradient at the interface between the solution and the bubble during dissolution, and to the mutual interactions during growth of the crystal. It was also observed that the growth rate anisotropy of the crystal was considerably influenced by the Marangoni convection. The growth rate was calculated assuming the process was con trolled solely by diffusion, which was compared with the observed values.
