Reconstruction of fracture surfaces on bornite

Synchrotron-radiation X-ray photoelectron spectroscopy (SRXPS) and conventional XPS have been used to study a pristine fracture surface of bornite. The main symmetric peak of the S 2p spectra for bornite is located at about 163.51 eV and is derived from bulk S atoms. The broad nature of the bulk contribution, in comparison to other 3d transition-metal sulphides such as chalcopyrite, is consistent with the presence of eight crystallographically distinct S sites within the structure, these sites being energetically as well as structurally distinct. A second peak at 160.1 eV is attributed to a surface monomeric species (S (super 2-) ) of lower coordination. The presence of a second broad surface-contribution at 162.1 eV probably represents surface polymeric species (S (super 2-) (sub n) ). The presence of surface sulphur polymers indicates the stabilization of the bornite surface upon fracture through formation of S-S bonds. These data suggest that surface polymers form where polar surfaces are exposed during conchoidal fracture. Conventional XPS Cu 2p and Fe 2p spectra collected from a pristine fracture-surface of bornite reveal a Cu (super 1+ ) peak centred at approximately 932.2 eV and a high-spin Fe (super 3+) peak centred at 708 eV.