Phase evolution and chemical durability of Nd-doped zircon ceramics designed to immobilize trivalent actinides

Zr 1− x Nd x SiO 4− x /2 (0≤ x ≤0.1) ceramics were prepared by solid-state reaction method. The effects of Nd content on the phase structure of the ceramics were investigated. The chemical durability of Nd-doped zircon ceramic waste forms was also examined. The results show that the ceramics with x <0.04 show homogeneous single zircon phase, while the samples with x ≥0.04 e x hibit coexistence of two crystal phases (zircon and Nd 2 Si 2 O 7 ). The bulk density of the Nd-doped zircon ceramics increases with the increase in neodymium content. Moreover, the normalized element release rates of Nd element in Nd-doped zircon ceramics firstly decrease with leaching time and almost no change after 14 days (~10 −4   g   m −2   d −1 ), demonstrating its good chemical durability. These results indicate that the obtained zircon ceramics waste forms are promising candidate for immobilization of trivalent actinides.