Synthesis and structure of Ce1−xEuxPO4 solid solutions for minor actinides immobilization

Abstract

Ce1−xEuxPO4 (x=0–1) solid solutions were synthesized by the solid state reaction process using europium (Eu) as the surrogate for trivalent minor actinide americium (Am). The effects of calcination temperature, holding time and Eu content on the crystalline phase, microstructure and morphology of Ce1−xEuxPO4 (x=0–1) were investigated. The monazite-type EuPO4 and CePO4 coexisted after being calcined at 1000°C for 4h, suggesting the CePO4 and EuPO4 phases would form initially separately. Pure and single-phase monazite-type Ce1−xEuxPO4 (x=0–1) powders were obtained at 1300°C for 4h. The results of the XRD patterns Rietveld refinement and μ-Raman analysis confirmed the formation of a Ce1−xEuxPO4 (x=0–1) continuous solid solution. The grain size of Ce0.5Eu0.5PO4 increased obviously as the holding time extended. The Ce, Eu, P and O elements were almost distributed homogeneously in the Ce0.5Eu0.5PO4 solid solution.