Verres du systeme La 2S 3La 2O 3Ga 2O 3Ga 2S 3

Abstract

The extent of the glass forming region is described as a function of the composition and of the cooling speed. The shape of this region is explained from the previously described La 2S 3La 2O 3Ga 2O 3Ga 2S 3 phase diagram. Glasses are obtained after relatively slow cooling (5°/min), in a definite region of compositions, which coincides with a relatively large concentration of ternary invariants. The thermal properties (transition temperatures and crystallization temperatures) were measured by DTA. For a relatively large region of compositions, glasses return to the equilibrium conditions with intermediate formation of the La 3.33Ga 6S 12O 2 metastable crystalline phase. An approach to the structure of the glasses is made by comparison with the crystal structures of the numerous ternary and quaternary crystalline compounds observed in the system, and by the comparison of the Raman spectra. It appears that these gallium oxysulfide glasses have many structural analogies with germanium sulfide glasses.