Structure and magnetic properties of Ni0.5Zn0.5Mn0.5-xMoxFe1.5O4 ferrites prepared by sol-gel auto-combustion method

A series of Mo doped Ni-Mn-Zn ferrites compounds with the formula Ni_0.5Zn_0.5Mn_0.5-xMo_xFe_1.5O₄ (x = 0, 0.025, 0.05, 0.075 and 0.1) were first synthesized by sol-gel auto-combustion method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM) analysis were carried out to characterize the microstructural and magnetic properties of ferrites. Rietveld refinement of X-ray diffraction data confirmed the formation of cubic spinel structure and the emergence of FeMoO₄ phase with the substitution of Mo⁶⁺ contents. The grain size increased remarkably due to the formation of the liquid phase. The saturation magnetization (M_s) increased while the coercivity (H_c) decreased from 67.3 to 12.1 Oe due to the decrease of magneto-crystalline anisotropy constant. The initial permeability (μ_i) increased significantly from 34 (x = 0) to 114 (x = 0.075) and later decreased for x = 0.1. In our experiment, Ni_0.5Zn_0.5Mn_0.425Mo_0.075Fe_1.5O₄ ferrite presented the best microstructure and soft magnetic properties.