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 Ni0.5Zn0.5Mn0.5-xMoxFe1.5O4 (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 (mu(i)) increased significantly from 34 (x = 0) to 114 (x = 0.075) and later decreased for x = 0.1. In our experiment, Ni0.5Zn0.5Mn0.425Mo0.075Fe1.5O4 ferrite presented the best microstructure and soft magnetic properties.