Enhanced magnetic properties of Gd³⁺-doped NiMgCu nano ferrites

NiMgCu spinel ferrite nanoparticles doped with Gd³⁺ in different ratios (Ni_0.3Mg_0.5Cu_0.2Gd_xFe_2−xO₄; x = 0.00, 0.02, 0.04, 0.06, and 0.08) were produced by citrate sol–gel auto-combustion. X-ray diffraction (XRD), field effect scanning electron microscopy, vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy were used to evaluate the structural and magnetic properties of the investigated samples. XRD powder diffraction patterns verified the spinel ferrite nanoparticle examined. The average crystallite size of the samples was calculated using the Debye–Scherrer formula. The average crystallite size dropped from 41.08 to 36.27 nm when the substitution of Gd³⁺ ions increased. Concurrently with the increasing Gd³⁺ ion abundance, the lattice constant rose from 8.3954 to 8.4287 Å. Using FE-SEM to examine the morphology of the synthesized ferrites revealed spherical-like structures with pores and aggregation. The 400–600 cm⁻¹ region of the FT-IR absorption spectra showed two absorption bands characteristic of spinel ferrites. The magnetic characteristics of the synthesized ferrite showed a reduction as the Gd³⁺ ion content increased. Both residual and saturation magnetization decreased, leading to a decline in magnetic stability. According to the VSM investigation, Gd³⁺ ion-doped NiMgCu ferrite exhibited ferromagnetism.