Comparison of phosphate-based glasses in the range 50P(2)O(5)-(50-x)CaO-xNa(2)O prepared using different precursors

The purpose of this study was to compare a range of phosphate-based glasses containing a fixed amount of (50 mol%) P2O5 and varying amounts of CaO and Na2O, made using two different sets of precursors in order to investigate any potential differences in their properties. Thermal analysis, XRD, dissolution, EDX, density, H-NMR and ion release studies were conducted in order to compare the data obtained from both groups. Thermal analyses revealed no differences in the glass transition temperatures obtained between the two groups, and similar crystalline phases were identified for each composition from both groups via XRD analysis. However, statistically significant differences were seen between the dissolution rates and density values obtained. The density values increased linearly with increasing CaO content, whilst the degradation rates decreased with increasing CaO content and spanned over four orders of magnitude. A decrease in the release of both cations and anions with increasing CaO content was also observed, with rates also ranging over four orders of magnitude. From the compositions investigated, the largest amounts of ions released were those of the Na+ and Ca2+ ions and the P2O93- anion, with higher total anion release observed from glasses prepared from one set of precursors than. the other. EDX analysis confirmed the composition of the glass formulations produced and no H+ ions were detected from 1H-NMR analyses conducted, suggesting that no H+ was present in the glasses produced