SHORT-RANGE ORDER DETAILS OF METAPHOSPHATE GLASSES STUDIED BY PULSED-NEUTRON SCATTERING

Details of the short-range order of the binary metaphosphate glasses A lP3O9 and PbP2O6 and the ternary glass system ZnO-MgO-2P(2)O(5) have b een studied by pulsed neutron scattering which provides a measuring ra nge up to about Q(max)=500 nm(-1). The splitting of the P-O peak in th e distance correlation functions attributable to the different bond le ngths for the non-bridging and bridging oxygens was found to decrease with increasing field strength of the network-modified cations. For th e ternary system ZnO-MgO-2P(2)O(5) the peak in the distance correlatio n fnction T(r), produced by the first oxygen neighbors around Zn2+ and Mg2+ was separated by the additional use of the X-ray structure facto r. The distances r(ZnO) and r(MgO) extracted from the separated peaks are slightly different from those obtained from the binary glasses ZnP 2O6 and MgP2O6. The metal-oxygen coordination numbers were found to be N-ZnO=4.5 and N-MgO=5.5. For the two binary systems the coordination numbers Al-O and Pb-O were obtained to be 7 and 5, respectively.