Effect of the Melting Conditions on the Uniformity of Chemical Composition in the As2S3 Glass

As2S3 glass rods were prepared by melting the raw materials in evacuated silica glass ampoules which had been placed horizontally in a rocking furnace, and cooled at vertical position. The effect of the melting temperature ranging 600-900°C on the uniformity of the chemical composition of the glass rod was studied. Maximum difference of the arsenic content at the each fraction of the glass rod, ΔAs, was employed as the evaluation of uniformity of the glass. To keep the ΔAs value less than 0.5wt%, melting time of 24h was required for melting at 600°C, 6h at 700°C, and 1h at 800°C. While only by heating up to 900°C, the ΔAs value went down to 0.3wt% and less. For the sample with poor uniformity, it was found that the arsenic contents in a lower half of glass rod (63-64wt%) was higher than the average arsenic content (60.9wt%).