Electronic structure of CuWO4: XPS, XES and NEXAFS studies

• Published in: Journal of alloys and compounds 2005-03, Vol.389 (1-2), p.14-20
• Main Authors: KHYZHUN, O. Yu, STRUNSKUS, T, CRAMM, S, SOLONIN, Yu. M
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Physics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2004.08.013

In addition to serving as a prospective precursor for synthesis of LixWO3 bronzes, CuWO4 was found to be a remarkable substance for synthesis of almost porosity-free W-Cu pseudoalloys containing 10-35 mol% of copper. X-ray photoelectron spectroscopy (XPS), X-ray emission spectroscopy (XES) and near-edge X-ray absorption fine structure (NEXAFS) methods were applied to study the electronic structure of copper tungstate, CuWO4. For the compound, XP valence-band spectra with different energies of excitation were studied, as well as the XE O Kalpha band and the NEXAFS O is spectrum were derived. The binding energies of the XP core-level electrons of the constituting elements of CuWO4 were measured. For comparison, some spectra of the hexagonal form of tungsten trioxide, h-WO3, were investigated. It was found that the half-width of the O Kalpha band decreases somewhat but that of the XP valence-band spectrum increases when going from h-WO3 to CuWO4, however the energy positions of the maxima and of the centres of gravity of the O Kalpha band remain constant for the above compounds. Measurements of the XP O is core-level binding energies and of the energy positions of the inflection point of the NEXAFS O Is spectra reveal that the effective negative charge of oxygen atoms in CuWO4 is close to that in h-WO3, while XPS W 4f core-level measurements reveal that the positive effective charge of tungsten atoms decreases somewhat in the sequence h-WO3 CuWO4.