Ground-based Experiments of Low Temperature Solution Crystal Growth in Space

To investigate the microgravity effect of low temperature solution crystal growth in space, an apparatus used for crystal growth of low temperature solution has been developed. In the apparatus the hydrophobic polytetrafluoroethylene membrane is first used to seal a growth container by employing the water-repellent and ventilate characteristics of the membrane. When a solvent (water) leaves the growth container by evaporation, and then is absorbed by an adsorbent at the outer of the container, the crystal growth can be continuously carried out. A series of growth experiments on the ground have been performed utilizing this apparatus, and a number of α-LiIO₃ crystals with large size and good quality have been obtained. It has been confirmed that the tightness of the membrane to seal a crystallizer and the evaporation capacity of a solvent through it can meet the requirement of low temperature solution crystal growth. A good foundation has been built for future crystal growth experiment in space.