Influence of rare earth addition on the thermal and structural stability of CaOFe2O3P2O5 glasses

The thermal and structural stability of calcium iron phosphate glasses doped with rare earth oxides has been studied by investigating differential scanning calorimetry, the concentration of modified ions in leachate, Fourier transform infrared spectra, and Raman spectra. The results showed that thermal stability of the rare earth phosphate glasses increased and the release rate of rare earth ions in leachate decreased with the increase of cationic field strength. It related to the known structural units and characteristic bands of these glasses detected by infrared and Raman spectra. Metaphosphate chains by the cross-links of calcium ions and POP linkages were easier to hydrolyze, which converted to orthophosphate units after corrosion. The formation of more chemically resistant REOP bonds with the addition of rare earth leaded to an increased quantity of nonbridging oxygen, which caused consequent variations in the chemical durability of rare earth glasses.