FT-IR Analyses of the Thermal and Oxidative Decomposition Products of Antimony Sulfides

A Nicolet Model 740 FT-IR spectrophotometer was used to analyze samples of the tri-, tetra-, and pentasulfides of antimony. These analyses were done in support of thermogravimetric analyses. The samples were scanned in the far-infrared (650 to 50 cm⁻¹) and the mid-infrared (5800 to 400 cm⁻¹) regions of the spectrum. The samples were prepared as pellets pressed in polyethylene powder to accommodate the far-infrared scanning. The analyses revealed that under thermal, nonoxidative conditions the tetra- and pentasulfides of antimony were converted to the trisulfide, while the trisulfide itself was unchanged. Analyses of the oxidatively stressed samples showed that all the antimony sulfides were converted to the cubic form of the trioxide of antimony at intermediate temperatures and to the tetraoxide of antimony at higher temperatures.