Atomic controllable anchoring of uranium into zirconate pyrochlore with ultrahigh loading capacity

Efficient immobilization of actinide wastes is challenging in the nuclear energy industry. Here, we reported that 100% substitution of Zr$^{4+}$ by U$^{6+}$ in a La$_{2}$Zr$_{2}$O$_{7}$ matrix has been achieved for the first time by the molten salt (MS) method. Importantly, we observed that uranium can be precisely anchored into Zr or La sites of the La$_{2}$Zr$_{2}$O$_{7}$ matrix, as confirmed by X-ray diffraction, Raman, and X-ray absorption spectra. This work will guide the construction of site-controlled and high-capacity actinide-immobilized pyrochlore materials and could be extended to other perovskite materials.