SYNTHESIS AND CHARACTERIZATION OF NICKEL ZINC FERRITES

Abstract

In this study we have prepared nickel ferrite (NF) and nickel zinc ferrite (NZF) nanoparticles by auto-combustion method starting from nickel, zinc and iron nitrates. After the process of self-ignition, fine precursor powder was thermally treated at 1000 °C for 1 h, forming nickel zinc ferrite powders, with molar ratio of Zn 0, 0.3, 0.5, 0.7. XRD characterization showed the formation of well crystallized nickel ferrite and nickel zinc ferrite inverse spinel structure without presence of secondary phases. Ceramic materials were obtained by uniaxial pressing at 196 MPa and sintering at 1250 °C for 4 h in the tube furnace. SEM images at the free surface showed that substitution of Ni2+ ions with Zn2+ ions results in larger grains and lower porosity, confirmed by density measurements. Magnetization results showed ferromagnetic behavior of the NF and NZF materials. Magnetic measurements of ferrites were carried out and presented in Fig. 1. Saturation magnetization moment of NF was lower than for N0.7Z0.3F and N0.5Z0.5F, but slightly higher than for N0.3Z0.7F. With increasing the ratio of Zn to 0.3, magnetization increases, because the Fe3+ ions in the octahedral site interact with other Fe3+ ions. The fields at which saturation occur was almost the same for all materials.