Structural investigation of iron sulfides synthesized by mechanochemical reaction

In the current study, pure elemental powders of Fe and S were mixed to give the desired compositions of Fe₆₇S₃₃, Fe₅₀S₅₀ and Fe₃₃S₆₇. A SPEX 8000D high-energy ball mill was used to synthesize iron sulfide powders under an Ar-filled atmosphere. The as-milled powders were examined by conventional X-ray diffraction (XRD) and synchrotron X-ray absorption spectroscopy (XAS). The experimental results showed that mechanochemical reactions occurred during the ball milling process for all the compositions investigated. The Fe_1-xS phase was observed at the end of milling. The formation time of the Fe_1-xS phase increased with increasing sulfur content. Extended X-ray absorption fine structure (EXAFS) results revealed that the nearest neighbor bond lengths of the radial distribution function for iron decreased when iron sulfides formed. X-ray absorption near-edge structure (XANES) of sulfar K-edge distinguished better the structural evolution of these iron sulfides.