The structure and properties of cesium loaded Mo-Fe-phosphate glasses

Chemically durable iron phosphate glasses are promising candidates for hosting nuclear wastes containing constituents like Cs2O and MoO3 that have lower solubility in more conventional borosilicate glasses. In this work, two series of Cs-Mo-Fe-phosphate glasses were prepared and characterized. For glasses in Series A (xCs(2)O center dot(100-x)center dot(15MoO(3)center dot 22.5Fe(2)O(3)center dot 62.5P(2)O(3)), x = 0, 7.5, 15.0, 22.5), increasing Cs2O contents increase the molar volume and decrease the glass transition temperature. Raman spectroscopy reveals that adding Cs2O breaks down linkages between MoO(6 )octahedra, replacing Mo-O-Mo and Mo=O bonds with Mo-O-Cs+ bonds. Phosphate anion chromatography reveals that adding Cs2O has little effect on the phosphate anion distributions. For glasses in Series B (15Cs(2)O center dot yMoO(3)center dot(28.75-y)Fe2O3 center dot 56.25P(2)O(5), y = 0, 5.75, 11.50, 17.25, 23.00, 28.75), the glass transition temperature decreases and the aqueous dissolution rates increase when MoO3 replaces Fe2O3. The formation of isolated MoO6 octahedra with Mo-O-Cs+ bonds results in an increase in the average phosphate anion-length in the MoO3 -rich glasses. Mossbauer spectroscopy indicates that ferric ions dominate in both series, and that the average Fe-coordination number increases with increasing Cs2O content (series A) and with increasing MoO3 content (series B).