Seedless crystallization of levitated Ge and GaSb spherical melts under microgravity

Seedless crystallization of Ge and GaSb melts was achieved under microgravi ty occurring in a drop-shaft capsule. It was observed that melts levitated in Ar atmosphere, formed into a spherical shape and were solidified instant aneously when they collided with the container quartz wall. X-ray diffracti on pattern of these samples showed clear Laue spots signifying a single-cry stal structure, while Ge or GaSb solidified in crucibles under normal gravi ty did not show Laue spots. These results indicate that single crystal grow th rapidly occurs without seed crystals from the spherical melt under micro gravity. This can be understood by assuming that an ordered structure Like a single crystal is already formed in a levitated melt, and assists rapid c rystallization when the melt touches the crucible wall and latent heat is d eprived.