Abstract
We report results of an extensive study of the viscoelastic response of several compositions of sodium ultraphosphate liquids. The study covers a wide compositional range from pure P(2)O(5) whose bridging oxygens form a three dimensional network to the sodium metaphosphate, NaPO(3), which form two dimensional chains. Spectra of the time-dependent structure factor were obtained using photon correlation spectroscopy and values of the glass transition, fragility, and the heterogeneity parameter have been determined. A decrease in fragility was observed with alklai addition which is shown to parallel changes in fragility occurring in alklai-free chalcogenide glass forming materials.