Milling-induced Amorphization in a Chalcogenide Compound

The mechanism of milling-induced amorphization was studied by investigating the structural evolution during amorphization via high-energy ball milling of a chalcogenide compound, i.e. Ag3PS4 crystal. The gradual decrease in intensity of the XRD diffraction peaks of Ag3PS4 milled for different durations indicates that the degree of amorphization was enhanced by the mechanical milling. The forward shift and evolution of the bimodal crystallization peak investigated by differential scanning calorimetry (DSC) imply that amorphization occurs from the surface state and extends to the bulk state until complete amorphization of the entire material. Furthermore, the Ag K-edge extended X-ray absorption fine structure (EXAFS) spectra manifest that during the milling, the Ag-S bonds in the Ag3PS4 crystal were broken firstly. Then, the distribution of Ag-S bond angels became wider and the coordination structure became more disordered with longer durations of mechanical milling.