Structural and magnetic properties of Ni–Cu–Co ferrites prepared from sol-gel auto combustion method with different complexing agents

Abstract

Sol-gel auto combustion method (EDTA, egg white, oxalic acid, tartaric acid and citric acid as a complexing agent) was used to prepare Ni–Cu–Co ferrite nanoparticles with the chemical composition of Ni0.2Cu0.1Co0.7Fe2O4. The phase formation has been confirmed by XRD patterns, which is a characteristic of spinel ferrite with most intense (311) peak. The crystallization of the material in the cubic spinel structure, the lattice parameter is approximately 8.38 Å. The average crystallite size of the samples prepared with different complexing agents ranged from 30 to 40 nm. The formation of spinel structure was also confirmed by Fourier transform infrared (FTIR) measurements. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicate the existence of spherically cubic shaped particles. The synthesized samples were demonstrated by energy dispersive X-ray (EDX) to have pure phase and structure, Ni, Cu, Co, Fe, and O were the main elements in Ni0.2Cu0.1Co0.7Fe2O4. Confirmed by X-ray photoelectron spectroscopy (XPS) cation redistribution of spinel ferrite nanoparticles. The magnetic parameters were measured by Vibrating sample magnetometer (VSM). Their ferromagnetic behavior was confirmed by observing the hysteresis loops of the samples. Compared with the samples prepared with other complexing agents (EDTA, egg white, tartaric acid and citric acid as complexing agents), the maximum of saturation magnetization and remanent magnetization were obtained for the sample prepared with oxalic acid as complexing agent. These ferrites have high coercivity. The sample prepared with oxalic acid has better magnetic properties than those samples prepared with other complexing agents. This indicates that oxalic acid as a complexing agent has stronger complexing ability for samples and less hydrolysis of metal ions in precursor solution than other complexing agents.