Structural, optical, and magnetic features of a rare-earth nanocomposite obtained from recycled NdFeB magnets

This work reports the synthesis and characterization of a rare-earth composite (Nd0.8Pr0.2)2O3/(Nd0.8Pr0.2)FeO3, obtained from end-of-life NdFeB magnets through an acid leaching route followed by controlled precipitation and thermal calcination. The developed process enabled the efficient recovery of neodymium, praseodymium, and iron in reactive forms, with high Nd/Pr recovery yields relative to the original magnet composition, highlighting the potential of the proposed route for applications aligned with circular economy principles. Compared to conventional recycling methods, such as pyrometallurgy and solvent extraction, the adopted strategy exhibits lower operational complexity, significantly reduced processing temperatures, and lower energy consumption, while avoiding the extensive use of high-impact organic solvents. Structural analysis by X-ray diffraction (XRD) combined with Rietveld refinement confirmed the formation of a biphasic crystalline system composed of a mixed orthorhombic perovskite and a cubic rare-earth oxide solid solution, with well-defined interfaces and evidence of partial Pr³+ incorporation into Nd³+ sublattices. Scanning electron microscopy (SEM) revealed a hierarchical and porous morphology, which is favorable for optical and catalytic-related processes. UV–Vis spectroscopy showed broad absorption in the 200–800 nm range, with two direct optical band gaps (1.8 and 3.1 eV) and an Urbach energy of 120 meV, indicating a moderate degree of structural disorder and efficient interfacial electronic coupling between the phases. Magnetic measurements revealed a hybrid magnetic behavior, with Ms ≈ 1.5 emu g−1, Hc ≈ 0.06 kOe, and SQR ≈ 0.34, reflecting the coexistence of antiferromagnetic and paramagnetic contributions. The combination of efficient rare-earth element recovery, reduced environmental impact, and the direct production of a functional composite with tunable optical and magnetic properties underscores the potential of this recycled material for advanced technological applications, particularly in optoelectronic devices, magnetic sensing systems, and other oxide-based multifunctional platforms, reinforcing the technological and environmental viability of NdFeB magnet recycling within the framework of the circular economy.