Crystallization process of lithium oxysulfide glasses

Crystallization kinetics and structural change during crystallization of the (100−x)(0.6Li2S·0.4SiS2)·xLi3PO4 oxysulfide glasses were investigated. The activation energies, Ea, for crystal growth estimated by the modified Kissinger equation ranged from 168 to 447 kJ/mol. The composition dependence of Ea showed opposite variation to that of the difference in the temperatures of crystallization and glass transition. This inverse correlation was explained in terms of the fragility of the oxysulfide system. Solid-state nuclear magnetic resonance (NMR) measurements revealed that the silicon and phosphorus atoms coordinated with both sulfur and oxygen atoms present in the oxysulfide glasses were not detected after crystallization. Relationship between the thermal stability of these glasses and the magnitude of the structural change during crystallization is discussed.