Effect of Al3+ ion-substituted Ni–Mg–Co ferrite prepared by sol–gel auto-combustion on lattice structure and magnetic properties

Abstract

In this paper, Al3+ ion substituted Ni–Mg–Co ferrite nano-magnetic material by sol–gel auto-combustion method. Citric acid is used as a complexing agent, and high-purity nitrate and deionized water are used as raw materials. And the effect of Al3+ ion substitution on the structure and magnetic properties of Ni–Mg–Co ferrite nanoparticles was studied. XRD analysis showed that all the samples have the characteristic peak of spinel ferrite. No impurity peaks were found, indicating that the ferrite has a single-phase structure. The average crystallite size was calculated by Debye–Scheller formula. With the increase of Al3+ ion substitution, the average crystallite size decreased from 58.3378 to 51.5249 nm. The structure of Ni–Mg–Co ferrite was characterized by FT-IR. There are two absorption bands ν1 and ν2 at 588 cm−1 and 389 cm−1, respectively, which further prove the spinel structure. The morphology of the samples was observed by SEM, and the particle size of the nanoparticles was calculated. The chemical composition of the sample was analyzed by EDS. The elements Ni, Mg, Co, Fe, Al, and O were found in the samples. By VSM analysis, it is found that Al3+ ion-substituted Ni–Mg–Co ferrite has ferromagnetic characteristics. With the increase of Al3+ ions substitution, the remanent magnetization (Mr), saturation magnetization (Ms), coercive force (Hc), anisotropy constant (K), magnetic moment (μB), and Yafet–Kittel angle (αYK) all decreased.