Effects of MoO3 and Nd2O3 on the structural features, thermal stability and properties of iron-boron-phosphate based glasses and composites

Three series of iron-boron-phosphate based glasses and composites as hosts for MoO ₃ and Nd ₂O ₃ were prepared by a melt-quenching process. The effects of MoO ₃ and Nd ₂O ₃ on phase composition, structural features, thermal stability and aqueous durability of the iron-boron-phosphate glasses and composites were investigated in detail. The results show that the 5∼15 mol% MoO ₃ containing samples with Nd ₂O ₃ content less than 3 mol% are fully amorphous, monazite NdPO ₄ phase is detected in their amorphous structure while more than 3 mol% of Nd ₂O ₃ incorporated. Generally, the incorporation of Nd ₂O ₃ and MoO ₃ enhances the crystallization of NdPO ₄ phase, and induces the decrease of Q ⁰ units and the increase of [MoO ₄], Q ¹ and Q ² units. Thermal stability of glassy phase in the samples is enhanced with the increase in MoO ₃ content, although its thermal stability decreases due to the formation of NdPO ₄ phase. Moreover, the reasons on the variations of structure and thermal stability are discussed. LR _Mo are about 10 ⁻⁴ ∼ 10 ⁻³ g·m ⁻²·d ⁻¹ for 14 days and LR _Nd are believed to be less than ∼10 ⁻⁶ g·m ⁻²·d ⁻¹, indicating their good aqueous durability. The conclusions provide researchers with the roles of MoO ₃ and Nd ₂O ₃ in iron-boron-phosphate based glasses and composites as potential hosts for Mo- and Nd-containing nuclear waste.