Effect of SrO content on the structure and properties of sodium-strontium metaphosphate glasses

In order to understand the influence of SrO content on the structure, physical properties and thermochemistry of sodium-strontium metaphosphate glasses, a series of glasses having the formula (50-x) Na2O-x SrO-50 P2O5, with x ranging from 0% to 50% molar, have been prepared by melt quenching technique. Fourier Transform Infrared Spectroscopy and 31P Magic Angle Spinning Nuclear Magnetic Resonance show the dominance of the metaphosphate species along the studied composition range, while increasing SrO led to the increase of the density, glass transition and crystallization temperatures and also the chemical durability, suggesting an increase of the reticulation of the phosphate network. The microcalorimetric dissolution in acid solution shows the decrease of the heat of dissolution as the SrO amount rises. Thermodynamic interpretations point out the occurrence of two composition domains, each one corresponding probably to the predominance of particular interactions.