The electronic structure of CuFeS2, chalcopyrite, from x-ray emission and x-ray photoelectron spectroscopy and Xα calculations

Abstract

The x-ray emission spectra (SKβ, SL, CuKβ, CuL, FeKβ, FeL) and x-ray photoelectron spectra of CuFeS2 chalcopyrite are reported and are interpreted using SCF-Xα MO calculations on the polyhedral anions CuS−74 and FeS−54 and discrete variational Xα band structure calculations. The highest energy occupied orbitals are found to be of Cu3d-S3p antibonding character. Substantial Fe3d character is observed across a broad range of binding energies indicating strong mixing of the Fe3d orbitals with both the Cu3d and S3p. Both the Xα cluster calculation on FeS−54 and the Xα band structure calculations overestimate the Fe3d orbital binding energies, although the discrepancy is smaller in the band calculation. Both computational methods predict the lowest energy empty orbitals to be of Fe3d-S3p antibonding character with a small (<2 eV) separation from the highest occupied orbitals. This small energy difference provides a possible explanation for the metallic conductivity observed in CuFeS2 at high pressure, particularly if the CuT–S bond is more compressible than the Feiii–S as is expected from compressibility-formal charge systematics.

The oxidation states of copper and iron in mineral sulfides, and the oxides formed on initial exposure of chalcopyrite and bornite to air

“…5b that the broader Cu L 3 peak situated $5 eV above the leading absorption peak would arise from transitions to Cu s-states and, to a lesser extent, Cu d-states. Most of the previous electronic structure calculations for chalcopyrite, including those using FEFF8 with the Hedin-Lundqvist exchange potential (Lavrentyev et al, 2004), are in broad agreement with the FEFF8 calculations carried out in the present study (Hamajima et al, 1981;Tossell et al, 1982;Petiau et al, 1988;Kurmaev et al, 1998;Edelbro et al, 2003).…”

Structural and optical properties of Fe and Zn substituted CuInS2 nanoparticles synthesized by a one-pot facile method

“…Figure 8 (C2 and C3) shows the effect of Zn substitution on size and morphology in comparison with pure CuInS 2 nanoparticles. [68][69][70][71][72] After substitution, it seems the valence or conduction band relocated respectively due to the p-d hybridization of Fe 3d-Cu 3d states mediated by the anion plike state or 4s state of Fe and Cu to generate a sub-band level (intermediate band) top of the valence band or below the conduction band. Recent studies have been indicated the binary, ternary or quaternary Zn-compounds are sensitive to different synthesis conditions (such as kind of zinc salt, sulfide source or solvent) for controlling of shape.…”

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

“…Recommended calibration values are 931.2 eV for the Cu L 3 peak in CuO and 707.7 eV for the Fe L 3 peak in Fe metal. All theoretical and experimental investigations recognise the covalent character of chalcopyrite which involves extensive overlapping of Cu and Fe metal d orbitals across the whole valence band (Tossell et al, 1982;Kurmaev et al, 1998;Edelbro et al, 2003).…”