Abstract
Pb_<1-x>Sn_xTe crystals were grown by the directional solidfication method under microgravity in the SL-J/FMPT mission on boad the space shuttle "Endeavour". A cylindrical crystal, 15 mm in diameter and 58 mm in length, was obtained. A constant SnTe mole fraction of about 0.16 (i.e., a constant Pb/Sn ratio) was achieved along the growth axis to a distance of about 10 mm, and the etch pit density is about one-tenth that of a terrestrially grown crystal. The space-grown crystal has also improved electrical properties. In addition, about 25 spherical crystals, ranging from 0.5 to 11 mm in diameter, were unintentionally formed on the graphite spring.Melt leakedfrom the reservoir into the spring enclosure and formed spherical melt drops in the hollow of the spring that solidified into spherical crystals during cooling. Some of the small crystals have low dislocation density, on the order of 10^4/cm^2, two orders smaller than terrestrially grown crystals.
