Crystal growth and transport rates of the GeSe-xenon system under microgravity conditions

The analysis of the STS-7 flight experiments of the GeSe-xenon system yielded positive results which surpass the original objectives of these experiments. The mass transport rates of GeSe observed in microgravity environment are in close agreement with theoretically predicted values for diffusion limited mass transport. This supports the earlier proposed hypothesis for the interpretation of flux anomalies observed in previous space experiments. In addition, the STS-7 flight experiments led to the observation of unexpected crystal growth phenomena. The largest GeSe single crystals obtained in microgravity grew in the ampul without direct wall contact which could suggest homogeneous nucleation. The space grown crystals are much larger and have considerably improved surface and bulk morphologies relative to corresponding ground control specimens. The combined results are of basic scientific importance and of technological significance.