Structure of alkali tungsten tellurite glasses by X-ray photoelectron spectroscopy

The electronic structure of two alkali tungsten tellurite glass series: (a) 10Li2O · xWO3 · (90 − x)TeO2, and (b) xK2O · (10 − x)Li2O · 25WO3 · 65TeO2 has been investigated by X-ray photoelectron spectroscopy. In contrast to alkali tellurite glasses, the core level spectra of the various elements appear unaffected when TeO2 is replaced by WO3, with the alkali oxide concentration remaining constant. The O1s spectra do not indicate a clear separation of the bridging and non-bridging oxygen contributions. Thus we conclude that WO3 behaves essentially as a network former in tellurite glasses. We have also obtained valence band spectra of the glasses and observed major changes with the addition of WO3. In particular, the intensity corresponding to the lowest energy part of the spectra, attributed to the O2p bonding orbital, decreases significantly with increasing WO3, indicating the appearance of a new bonding configuration.