Effect of Gd³⁺ Substitution on the Structural, Magnetic, and Dielectric Behaviour of Ni₀.₇Co₀.₃Fe₂O₄ Ferrites"

Abstract:This study investigates the structural, magnetic, dielectric, and morphological properties ofNi0.7Co0.3GdxFe2−xO4 (where x = 0.00 and 0.015) ferrite nanopar,cles synthesized via a wet chemicalmethod. X-ray diffraction (XRD) analysis reveals that Gd3+ doping leads to a slight increase in la4ceconstant from 8.3502 Å to 8.3545 Å, indicating lattice expansion due to the substitution of largerGd3+ ions for Fe3+. The crystallite size decreases from 35.93 nm (pure Ni-Co ferrite) to 23.39 nm forthe Gd-doped sample, which is attributed to lattice distortions that hinder crystal growth. FieldEmission Scanning Electron Microscopy (FE-SEM) images show that the particles exhibit a sphericalmorphology and significant agglomeration, a typical feature of ferrite nanoparticles. Magneticmeasurements performed using a vibrating sample magnetometer (VSM) indicate an increase insaturation magnetization (from 30.67 emu/g to 35.41 emu/g) and remanent magnetization (from15.87 emu/g to 17.81 emu/g) with Gd doping. Coercivity decreases slightly, suggesting enhanceddomain wall mobility. Dielectric studies show an increase in dielectric constant, particularly at lowerfrequencies, due to enhanced polarization mechanisms facilitated by Gd3+ subs,tu,on. Thesefindings demonstrate that Gd doping improves the multifunctional properties of Ni-Co ferrites,making them suitable for applications in high-frequency electronic devices, magnetic sensors.