The Structure of a Zn(Ⅱ) Metaphosphate Glass. Ⅰ. The Cation Coordination by a Combination of X-Ray and Neutron Diffraction, EXAFS and X-Ray Anomalous Scattering

摘要

In order to clarify the reason of some discrepancies existing in literature, the zinc coordination in a Zn metaphosphate glass has been investigated by the complementary use of X-Ray Diffraction, Neutron Diffraction, Extended X-ray Absorption Fine Structure Spectroscopy and X-Ray Anomalous Scattering. All the techniques indicate a tetrahedral coordination of O atoms around Zn~(2+) ions, the Zn-0 distance being 1.94 ± 0.01 A. The simultaneous modelling of all the experimental data by Reverse Monte Carlo technique demonstrated that this coordination is consistent with an extended model in which metal ions are interposed between phosphate chains. The importance of describing the preparation conditions of the glasses is stressed when structural results have to be compared.