Influence of annealing temperature on structural, magnetic, and dielectric properties of NiFe2O4 nanorods synthesized by simple hydrothermal method

Abstract

In this study, the one-dimensional (1D) nanostructures of nickel ferrite were synthesized using a hydrothermal method and heat treatment at different temperatures. The morphology, crystallinity, magnetic, and dielectric properties of the prepared samples were considered with respect to the calcination temperature. Thermogravimetric analysis (TGA), differential thermal analysis (DTA), and X-ray diffraction (XRD) studies of the precursor and annealed samples confirmed the formation of nickel ferrites in the pure phase. The XRD analysis (crystallite size, lattice constant, and density) show achieving high crystallinity and inverse-spinel structure during the calcination temperature variation. Moreover, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images, indicated that a 1D nanorod structure with a high aspect ratio was successfully produced and morphology variation was observed during calcination at 400–900 °C. The N2 adsorption-desorption hysteresis loop confirmed the mesoporous features. The magnetic characteristics were determined using vibrating sample magnetometer (VSM) analysis. The saturation and remanence magnetization increased, whereas the coercivity increased and then decreased as the calcination temperature is increased. The coercivity peak can be interpreted by magnetocrystalline anisotropy. The polarization at the boundaries illustrates the reduction in the dielectric characteristics as a frequency is increasing.