Crystallization in 70Ga(2)S(3)center dot 30La(2)S(3) (mol%) glasses as a function of oxide/hydroxide concentration

The crystallization of 70Ga(2)S(3). 30La(2)S(3) (mol%) glasses has been stu died using X-ray diffraction and transmission electron microscopy. Two of t he glasses were prepared from raw materials with nominally different oxide concentrations. The third was prepared from raw materials aged in an oxygen -depleted, argon-flushed glove box for more than 1 yr. Their oxide/hydroxid e impurity content was qualitatively ranked using Fourier transform infrare d spectroscopy. The lowest oxide content composition (less than or equal to 0.5 wt%, supplied information) devitrified readily close to the glass tran sition temperature, T-g, forming crystallites of a new (GLS) phase with a m onoclinic Bravais lattice and a lathlike internal structure. Ga2S3 was obse rved in small quantities between the laths. Samples prepared from nonaged, high oxide (1-3 wt%) content precursors produced the most stable glass. On crystallization, these samples exhibited spherulites composed of intergrown laths of melilite-structured La3.33Ga6S14 and the new monoclinic GLS phase . Whiskers of Ga2S3 were found in the residual glass between crystallites. Samples prepared from aged raw materials produced spherulites of La3.33Ga6S 14 on crystallization with no identifiable regions of the new GLS phase.