Effects of Ce+Gd on the structural features and thermal stability of iron-boron-phosphate glasses

In this paper, effect of Ce + Gd incorporation on the structural features and properties of iron borophosphate (IBP) glasses was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetric (DSC) measurements. The results show that the solubility limit of Ce + Gd in the IBP glass with the composition of 36Fe2O3-10B2O3-54P2O5 is about 8 mol%. The structural networks of the Ce + Gd containing IBP glasses consist predominantly of orthophosphate, Q0, groups and pyrophosphate, Q1, groups, along with [BO4] units and a small amount of metaphosphate, Q2, groups. The Ce + Gd incorporation increases the density and Tg but decreases thermal stability of the IBP glass. However, the thermal stability of the Ce + Gd doped IBP glasses increases with Ce + Gd until the contents of Ce + Gd nearly reach the limit solubility. Moreover, the incorporation of Ce + Gd offers depolymerizing effect on the glass networks, which increases the fraction of Q0 and Q1 groups, and decreases the fraction of Q2 groups. The conclusions provide researchers with useful information to understand the roles of Ce + Gd in iron-boron-phosphate based glasses for high-level nuclear waste immobilization.