New method for preparation of specially pure glasses in the Ge-S-I system by melting the products of thermal decomposition of Ge2S3I2

Ge-S-I glasses having iodine content of 4.0-22.1 at.% and the x(S)/x(Ge) ratio of 1.7-2.1 were prepared by melting and subsequent cooling of the products of thermal decomposition of Ge2S3I2. The maximum temperature of synthesis was 550 °С, and the homogenization duration of the glass-forming melt at 750 °С was 1 h. The compositions and properties of the resulting glasses and the impurity content in samples obtained under different conditions of Ge2S3I2 decomposition were investigated. The purest samples of prepared glasses were characterized by high optical transparency in the spectral range of 2-10 μm and the low content of impurities: silicon (0.1 ppm wt), metals (< 0.5 ppm wt) and hydrogen in the form of S-H bonds (0.02 ppm wt).