Coordination change of Te atoms in binary tellurite glasses

Coordination changes of Te(+ IV) atoms were derived from Raman and X-ray photoelectron spectra of the binary tellurite glasses containing Li, Na, Ba and Zn. A structure model consistent with the experimental results was proposed. In this model, TeO₄ units were converted mainly to O _{2 2}Te=O and O _{1 2}Te(=O) O^- in the range of lower atomic ratio O/Te, and the rate of increase of TeO₃/TeO₄ decreased in the range of higher O/Te because of the equilibrium TeO _{4 2} ↔ O _{2 2}TeO. The increase in the fraction of non-bridging oxygen atoms and three-coordinated Te(+ IV) atoms was confirmed by X-ray photoelectron spectra. The fraction of non-bridging oxygen estimated from X-ray photoelectron spectra agreed well with that from the Raman spectra and the model.