Effect of La³⁺ substitution on structural and magnetic parameters of Ni–Cu–Zn nano-ferrites

The ferrite material with compositions Ni_0.7Cu_0.1Zn_0.2La_xFe_2−xO₄ (where x = 0, 0.015, 0.025, and 0.035) was synthesized by oxalate co-precipitation method. The ferrite samples were characterized by thermo-gravimetric and differential temperature analysis (TG–DTA), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM) techniques. The EDAX analysis confirmed the formation of required stoichiometric ferrite samples. The formation of cubic spinel structure with the presence of weak ortho-ferrite phases was confirmed from X-ray diffraction analysis. The lattice constant of all the ferrites was found to be increase with increase in La³⁺ content. The presence of main two recognized strong absorption bands in the frequency range 400–600 cm⁻¹ in the FTIR spectra shows the formation of well spinel ferrite. Morphological study shows that grain size of the ferrites lies in the range 16.23–24.21 nm. It is observed that the saturation magnetization and magnetic moment of Ni–Cu–Zn ferrites decrease with La³⁺ content.