XPS and magnetic studies of vanadium tellurite glassses

• Published in: Journal of electron spectroscopy and related phenomena 2009-12, Vol.175 (1), p.21-26
• Main Authors: Mekki, A., Khattak, G.D., Wenger, L.E.
• Format: Article
• Language: eng ; fre ; ger
• Subjects: Magnetic susceptibility of vanadate glasses; Vanadium tellurite glasses; XPS study of vanadate glasses
• ISSN: 0368-2048; 1873-2526
• DOI: 10.1016/j.elspec.2009.07.001

A series of tellurite glasses containing vanadium with nominal composition xV 2O 5–(1 − x)TeO 2, 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 TeO 4 trigonal bipyramid (tbp) configuration and the other from Te ions in TeO 3 trigonal pyramid (tp) configuration. Quantitative analysis of the areas of both components support the model of a change of TeO 4 tbp to TeO 3 tp upon V 2O 5 addition. The V 2p core level spectra did not show any asymmetry and were fitted with a single component corresponding to V 5+ 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 V 2O 5 content suggesting the formation of TeO 3 units and also that V 2O 5 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 V 5+. The ratios of V 4+/V total as determined from magnetic susceptibility measurements assuming only the presence of magnetic V 4+ and non-magnetic V 5+ 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.