Phase formation during crystallization of melts and glasses of the GaxGe40-xS60 system

Abstract

The purpose of this work is to study phase formation during quenching of glass-forming melts and crystallization of GaxGe40-xS60 glasses (x = 0–15 at.%), which are promising materials for optical IR glass-ceramics. The stability against crystallization of the glasses is determined to decrease with increasing gallium content. In the case of the glass-forming melts, the stability against crystallization increases in the range x = 0–8 at.% and then decreases. It is established that, during crystallization, not pure phases of binary sulfides are formed, but their solid solutions. When quenching the melts with a gallium content of 10–15 at.%, Ga2-xGexS3 solid solutions, which are isostructural to one of the polymorphic modifications of gallium sesquisulfide, are crystallized. Solid solutions form skeletal crystals, the growth of which leads to the formation of a dendritic crystal structure. Micro-liquation in the GaxGe40-xS60 glasses is observed.