Measurement of solutal and thermal diffusion subjected to rapid cooling in microgravity and crystal growth

In the process of crystal growth in solution under the normal gravity environment, double diffusive convection occurs due to the thermal and solutal gradients. The natural convection disturbs pure thermal and solutal diffusion field around a seed crystal, and the phase change phenomena in diffusion process can not be seen directly. Microgravity environments generated by parabolic flights for 20 s were used in order to suppress the double diffusive convection. In-situ measurement of the diffusion field was carried out using a real-time phase-shift interferometer. The saturated solution around a seed cryrtal of NaC103 was subjected to rapid cooling for the duration of microgravity by Peltier elements in the test cell. The test cell was subjected to a number of temperature profiles during microgravity experiments. In particular, the measured diffusion phenomena subjected to rapid cooling can not be explained by a conventional diffusion process nor kinetics of crystal growth.