Copper oxidation state in chalcopyrite:: Mixed Cu d9 and d10 characteristics

The determination of the oxidation states of copper and iron in sulfides, and chalcopyrite (CuFeS2) in particular, using 2p X-ray photoemission spectroscopy (XPS) and L-2,L-3-edge X-ray absorption spectroscopy (XzAS) is revisited. Reassessment of the published spectra derived by these methods produces consistent results and reveals the 'd count' in the copper compounds to be intermediate between d(9) and d(10). Nevertheless, these covalent copper compounds can be divided into those nominally monovalent and those nominally divalent. The Fe L-2,L-3-edge XAS of chalcopyrite, along with Mossbauer data, confirm the presence of high-spin Fe. Chalcopyrite, despite recent published reports to the contrary, clearly belongs to the monovalent copper class. (c) 2006 Elsevier Inc. All rights reserved.