Phase and microstructure evolution of 0.2SiO2/Zr1-xNdxSiO4-x/2 (0 ≤ x ≤ 0.1) ceramics

Zircon (ZrSiO4) ceramics were widely used in the field of nuclear waste immobilization because of their excellent properties. However, the SiO2/ZrSiO4 ceramics were usually obtained in the preparation of ZrSiO4. The actinides immobilization behavior of SiO2/ZrSiO4 ceramics is unclear. Herein, Nd-doped 0.2SiO2/Zr1-xNdxSiO4-x/2 (0≤x ​≤ ​0.1) ceramics were fabricated and the effects of Nd-doping and sintering temperature on their phase and microstructure evolution were investigated. The obtained ceramics were characterized by XRD, SEM, BSE and EDS. Results show that 0.2SiO2/Zr1-xNdxSiO4-x/2 ceramics with 0≤x ​< ​0.04 are ZrSiO4 phase; while with 0.04≤x ​≤ ​0.1 are coexistence of ZrSiO4 and Nd2Si2O7 phases. The solubility limit of Nd3+ in 0.2SiO2/ZrSiO4 is about 4 ​at%. The lattice volume of ZrSiO4 increased with increasing Nd-doped content and sintering temperature. Furthermore, higher Nd-doped content and sintering temperature are beneficial to the densification of the obtained ceramics. The results demonstrate that the 0.2SiO2/ZrSiO4 ceramics can be employed as waste form materials to immobilize trivalent actinides.