Evidence for symmetric cationic sites in zirconium-bearing oxide glasses

The local environment of Zr in a borosilicate glass has been investigated by combining molecular dynamics (MD) simulations with Zr K-edge x-ray absorption spectroscopy (XAS) measurements. Two- and three-body distribution functions in agreement with the experimental data were obtained. The oxygen first neighbors around Zr are found to be narrowly distributed, revealing almost perfectly regular ZrO6 octahedra. Significant three-body contributions (Zr-O-O) to the XAS signal are observed, probing the existence of highly symmetric cationic sites in a glassy network. The g(ZrO)(r) first peak derived from the experimental data is narrower than the one given by the MD model, thus providing elements for further improvements of the MD potentials.