Crystal growth in a microgravity environment

Abstract

Gravitational phenomena, including convection, sedimentation, and interactions of materials with their containers all affect the crystal growth process. If they are not taken into consideration they can have adverse effects on the quantity and quality of crystals produced. As a practical matter, convection and sedimentation can be completely eliminated only under conditions of low gravity attained during orbital flight. There is, then, an advantage to effecting crystallization in space. But in the absence of of convection in a microgravity environment cooling proceeds by thermal diffusion from the walls to the center of the solution chamber. This renders control of nucleation difficult. Accordingly there is a need for a new and improved nucleation process in space. Herein crystals are nucleated by creating a small localized region of high relative supersaturation in a host solution at a lower degree of supersaturation.