Nd-modified NiFe2O4 nanoparticles for enhanced X-band electromagnetic wave absorption

Doping rare-earth (RE) elements into ferrites is an effective strategy for modifying their physical structure, magnetic response, and electromagnetic-wave absorption behavior. In this study, nickel ferrite nanoparticles were modified with a small amount of neodymium (Nd) using a simple coprecipitation method. The influence of Nd content on morphology, crystal structure, elemental composition, magnetic properties, and X-band absorption performance was investigated using SEM–EDX, XRD, EDX mapping, VSM, and vector-network-analyzer measurements. The novelty of this work lies in systematically correlating low-level Nd incorporation with microstructural evolution, particle dispersion, magnetic parameter modulation, impedance matching, and X-band microwave absorption performance of NiFe 2 O 4 nanoparticles. The results confirmed the successful formation of Nd-modified nickel ferrite materials with different Nd contents. Nd incorporation reduced nanoparticle agglomeration and altered the magnetic parameters, particularly saturation magnetization and coercive field, thereby improving impedance matching and electromagnetic-wave attenuation in the 8–12 GHz range. The strongest reflection loss reached −25.47 dB at 11.56 GHz for the NiFe 1.97 Nd 0.03 O 4 sample at a matching thickness of 2.0 mm, corresponding to an electromagnetic-wave absorption efficiency of approximately 99.7%. These results indicate that Nd-modified NiFe 2 O 4 nanoparticles are promising candidates for X-band electromagnetic-wave absorption and shielding applications.