Ultrafast mechanochemical synthesis of copper sulfides

Abstract

Covellite, CuS and chalcocite, Cu₂S were prepared within a few seconds by ball milling of the elemental precursors. The morphology of the used copper, related to its preparation method, was found to be the key factor for the ultrafast reaction. The explosive character of the reaction was monitored by the gas pressure changes in the milling vessel and the reaction progress was pursued by X-ray diffraction analysis and Soxhlet's extraction. The local temperature at the contact site between the milling media and the milled mixture at the time of explosion was calculated as 950 °C for CuS and 700 °C for Cu₂S. The mean crystallite size of the prepared products was 15 nm for CuS and 65 nm for Cu₂S.