Local structure and redox state of vanadium in vanadium strontium borate [(V2O5)0.5(SrO)0.5-y(B 2O3)y] oxide glasses

G. D. Khattak, Nouar Tabet, A. Mekki

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Abstract

The local structure of vanadium strontium borate glasses with the nominal composition [(V2O5)0.5(SrO)0.5-y (B2O3)y], where 0.1≤y≤0.4, as well as the valence state of the vanadium ions have been investigated by x-ray photoelectron spectroscopy (XPS). The core level binding energies of V 2p, Sr 3p, B 1s and O 1s have been measured. It was observed that there is a small increase in binding energies of the doublet peaks attributed to Sr 3p 3/2 and Sr 3p1/2 in the Sr 3p spectra with an increase in the B2O3 content and also shifted by ∼ 0.6 eV towards higher binding energies in comparison to their values in SrO powder. The binding energies of the B 1s peak positions increase with an increase in the B 2O3 content, have essentially the same FWHM but, in comparison to B2O3 powder, the peak positions have shifted towards lower binding energy side by ∼0.7 eV. The O 1s core level spectra, however, show asymmetry for all glass samples which results from two contributions, one from the presence of oxygen atoms in the V-O-V, V-O-B, B-O-B environment (bridging oxygen BO) and the other from oxygen atoms in V-O-Sr, B-O-Sr, V=O, environment (non-bridging oxygen NBO). The O 1s core level spectra were deconvoluted into two peaks (BO and NBO) and the ratio of NBO to total oxygen was found to decrease with increasing B2O3 content. The quantitative ratio, [V4+/Vtotal], for each glass sample, has been determined from the analysis of the V 2p core level spectra. The ratio remains practically constant, independent of vanadium concentration within experimental uncertainties.

Original languageEnglish
Pages (from-to)165-169
Number of pages5
JournalPhysics and Chemistry of Glasses
Volume46
Issue number2
Publication statusPublished - 1 Apr 2005
Externally publishedYes

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Ceramics and Composites

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