Tuning structural, magnetic, electrical, and dielectric properties of MgFe2O4 synthesized by sol-gel followed by heat treatment

Abstract

We investigated magnesium ferrite MgFe2O4 nanoparticles synthesized by the sol-gel method followed by heat treatment at distinct temperatures. Specifically, we evaluated the influence of the heat treatment on the structural, magnetic, electrical, and dielectric properties of particles with dimensions of nm. Then, we brought a route, a synthesis method followed by heat treatment, that provide us the high control of the particle composition and particle size. X-ray diffraction analysis and transmission electron microscopy images revealed the formation of pure magnesium ferrite nanoparticles, with increasing average particle diameter with treatment temperature. The modifications of the structural parameters were correlated with the cation distribution between the tetrahedral (A) and octahedral [B] sites of the magnesium ferrite, which evolves with the increase of the Mg2+ ions at the [B] site as the heat treatment temperature is raised. The changes in the structural features induced by heat treatment at distinct temperatures led to modifications in the magnetic and dielectric properties of the ferrites. Magnetic characterization disclosed a dependence of the magnetic parameters with the treatment temperature. On the electric features, a decrease in the electrical resistivity with the treatment temperature was found, a fact primarily due to the increase of the grain size and the cation distribution of Mg and Fe. Regarding the dielectric characteristics, we disclosed low values for the dielectric constant and dielectric loss factor for the whole range of frequencies (0.1 up to 1.5 GHz), despite the dependence with the heat-treatment temperature and evolution with probe frequency. Through Mössbauer experiments, we elucidated the conduction mechanisms in our MgFe2O4 ferrite. Our results demonstrate that the structural, magnetic, electrical, and dielectric properties of MgFe2O4 nanoparticles can be tuned by the synthesis method followed by heat treatment. All these features place the magnesium ferrite MgFe2O4 nanoparticles, synthesized by sol-gel followed by heat treatment at distinct temperatures, suitable for sensor elements in technological devices and microwave applications.