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Abstract: A series of tellurite glasses containing vanadium with nominal composition xV2O5–(1− x)TeO2, where x =0.1, 0.2, 0.3, and 0.4, have been prepared by melt quenching technique and investigated using X-ray photoelectron spectroscopy (XPS) and magnetization techniques. The Te 3d core level spectra show asymmetry and therefore were fitted with two contributions one from Te ions in TeO4 trigonal bipyramid (tbp) configuration and the other from Te ions in TeO3 trigonal pyramid (tp) configuration. Quantitative analysis of the areas of both components support the model of a change of TeO4 tbp to TeO3 tp upon V2O5 addition. The V 2p core level spectra did not show any asymmetry and were fitted with a single component corresponding to V5+ while the O 1s core level spectra show slight asymmetry on the higher binding energy side of the main peak and were fitted with two contributions, one due to bridging oxygen (BO) atoms and the other due to non-bridging oxygen (NBO) atoms. The fraction of NBO, determined from these spectra, is found to increase with increasing V2O5 content suggesting the formation of TeO3 units and also that V2O5 is acting as a glass modifier in this glass series. The magnetic susceptibility data for these glasses follow a Curie–Weiss behavior (M/H = C/(T − θ)) which also indicates the presence of some V ions existing in a magnetic state, i.e., a valence state other than that of the non-magnetic state V5+. The ratios of V4+/Vtotal as determined from magnetic susceptibility measurements assuming only the presence of magnetic V4+ and non-magnetic V5+ ions vary from 0.030 to 0.037. These ratios are too small to be detected by XPS measurements and this is why no asymmetry is observed in the V2p spectra of these glasses. [Copyright &y& Elsevier]

Sodium tellurite glasses containing CuO with the nominal composition [(Na2O)0.3(TeO2)0.7−x (CuO)x], where x=0.00, 0.05, 0.15, and 0.20, have been prepared and investigated by X-ray photoelectron spectroscopy (XPS). The binding energies of Te 3p, Te 3d, O 1s, and Cu 2p core levels in these glasses have been measured and compared to the corresponding binding energies in TeO2 and CuO powders. The Te 3p and Te 3d core levels for the glasses were essentially unchanged from those of TeO2 powder and have little dependence upon the CuO content. Although the O 1s peak showed a small asymmetry on the higher energy side of the peak in the glasses, it was primarily the result of hydroxide contamination on the glass surface rather than the appearance of non-bridging oxygen atoms arising from a structural change in the TeO4. For glasses with x=0.05 and 0.15, the Cu 2p peaks were shifted by more than 1 eV towards lower binding energies in comparison to their values in CuO powder, which suggests the presence of Cu+ ions in these glasses. The appearance of satellite peaks in the Cu 2p spectra, however, provided definitive evidence for the presence of Cu2+ ions in these glass samples as well. The broadened Cu 2p3/2 peaks were correspondingly decomposed into two distinct peaks separated by approximately 1.25 eV, with the lower energy peak being associated with Cu+ and the higher one with Cu2+. The relative Cu2+ content estimated from the spectral analysis was found to vary from 15% for the x=0.05 glass sample to over 70% for the x=0.20 sample. [Copyright &y& Elsevier]