Nd 3+ -Doped Fe 3 O 4 With Tunable Magnetism and Ultrahigh Solubility: A Dual-Functional Matrix for Advanced Nuclear Waste Encapsulation

How to simply and efficiently handle high-level radioactive waste is crucial for the sustainable development of nuclear energy. In this work, a solid solution of Fe3-xNdxO4 (0 ≤ x ≤ 0.9) was successfully synthesized by co-precipitation, with Nd(III) as a simulated radionuclide. The solid solution was characterized using inductively coupled plasma optical emission spectrometry, X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), etc. The results show that Nd(III) can be effectively incorporated into the Fe3O4 lattice via a substitutional doping mechanism. As x (0 ≤ x ≤ 0.9) increases, Fe3-xNdxO4 transitions from an inverse spinel to a more stable orthorhombic structure, enhancing the solid solution’s capacity.XPS and FTIR analyses revealed that Nd(III) replaces Fe(III) in the lattice, forming new bonds with oxygen, while excess Nd(III) bonds with surface-adsorbed oxygen without changing its oxidation state. Vibrating sample magnetometer measurements indicated that the solid solutions maintain a high saturation magnetization and possess strong magnetic properties. By adjusting the Nd content, the magnetic properties of Fe3-xNdxO4 can be tuned for efficient recycling and separation. This work introduces a novel waste solidification matrix with high nuclide loading and easy recovery, offering a new strategy for nuclear waste reduction and recycling.