Fracture-induced reconstruction of a chalcopyrite (CuFeS2) surface

Two factors contributing to the high binding energy asymmetry of the S 2p XPS peak for virginal chalcopyrite (CuFeS2) surfaces have been identified. The Cu, Fe and S 2p spectra of freshly fractured surfaces of chalcopyrite have been found to display a loss feature at similar to2.6 eV that is attributed to an interband transition S 3p --> Fe 3d, from occupied S levels to unoccupied Fe levels. For leached chalcopyrite systems, intensity on that side of the S 2p peak sometimes has been interpreted erroneously in terms of oxidized species such as polysulphides. A second prominent S 2p component has been determined at a binding energy of 161.9 eV and identified as the sulphide dimer S-2(2-). With supporting evidence, a simultaneous surface reconstruction and redox reaction model has been developed for the fracturing of chalcopyrite, leading to an exposed surface phase of about two layers thick with a 50% pyritic content. The pyritic nature of the fractured chalcopyrite surface has implications for understanding the leaching chemistry of chalcopyrite. Copyright (C) 2003 John Wiley Sons, Ltd.