X-ray photoelectron spectroscopic studies of zinc-tellurite glasses

Zinc-tellurite glasses with chemical composition [(ZnO)(x)(TeO2)(100-x)], where x=25, 30 and 35 have been prepared and investigated by X-ray photoelectron spectroscopy (XPS). Zn 2p peaks shift by about 0.25 eV towards higher binding energy in the zinc-tellurite glasses in comparison to its value in ZnO powder, while the Te 3p, Te 3d, and O 1s core levels for the glasses remain essentially unchanged from those of TeO2 powder. Each O is spectrum is deconvoluted into two peaks, in which the higher energy one is due to oxygen atoms in the hydroxides covering the sample surface. Although both bridging oxygen (BO) and non-bridging oxygen (NBO) atoms should certainly exist in these tellurite glasses, the electrons are delocalised in the NBO-Te-BO bonds which equalize the electronic density of the valence shell between BO and NBO atoms and make it difficult to distinguish. (C) 2002 Elsevier Science B.V. All rights reserved.