ON THE DENDRITES AND DENDRITIC TRANSITIONS IN UNDERCOOLED GERMANIUM

Undercooled molten Ge was allowed to solidify at initial bulk undercoo lings, DELTAT, from 10 to 200-degrees-C under dehydrated boron oxide f lux. It turned out that in addition to the [211] twin dendrite found b y Billig and the [100] twin-free dendrite discovered by Devaud and Tur nbull, there is a third novel twin dendrite, the [110] twin dendrite. The twin planes in a [110] dendrite always appear in multiple numbers and the orientation is {111}. These different kinds of dendrites exist at different initial interfacial under coolings and the transition te mperatures for [110] to [211], [211] to [100] are DELTAT = 61 and 93-d egrees-C, respectively.