X-ray photoelectron spectroscopy of alkali tellurite glasses

X-ray photoelectron spectra of R(2)O-TeO2 (R: Li, Na, K, Rb and Cs) glasses were measured, using a fresh surface fractured in an ultra high vacuum (approximate to 7 x 10(-8) Pa) and irradiated with a monochromatic Al K alpha X-ray (hv = 1486.6 eV). The O Is photoelectron spectra showed only a single Gaussian-Lorentzian peak and the peak shifted toward smaller binding energy with increase in Lewis basicity of oxide ions in the glasses. Two peaks attributed to BO and NBO were not observed, In the near valence band spectra for the lithium tellurite glasses, the spectral profile gradually became similar to that of a Li2TeO3 crystal with increase in Li2O content up to 30 mol% Li2O. This variation of the profile is correlated to the change in the coordination structure of the tellurium atoms (TeO4 trigonal bipyramids --> TeO3 trigonal pyramids) with the addition of the alkali oxides.