Structural, dielectric and magnetic properties of zinc-aluminum co-substituted in cobalt ferrite nanoparcticles synthesized via co-precipitation method

Abstract

Spinel ferrite nanoparticles (NPs) have raised interest due to their technological applications. Fabrication of doped cobalt (Co) ferrite NPs with high crystallinity, good dielectric and modified magnetic properties are demanded for many applications. This thesis determined the influence of zinc-aluminum substitution on the structural, dielectric and magnetic properties of Co ferrite NPs. A series of Co(1-x)Zn(x)Fe(2-x)AlxO4 NPs with 0.0 = x = 1.0 (x in wt.%) were prepared by chemical co-precipitation method and calcined at 700 °C, 800 °C and 900 °C. The synthesized samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field-emission scanning electron microscopy (FESEM), Vibrating sample magnetometer (VSM) and the Impedance Analyser. The achieved high crystallinity and formation of spinel structure with mean particle size 17–30 nm is confirmed by XRD analyses. The FESEM micrographs displayed the formation of well-defined and homogenous crystalline grains having Gaussian size distribution with narrow open pores. FTIR spectra revealed two absorption bands which confirmed the presence of A and B sublattices for the spinel structure. The values of saturation magnetization and magnetic coercivity were increased from 13.80–88.61 emu/g and 23.99–109.63 Oe, respectively as the temperature was increased from 700 °C to 900 °C. The room temperature dielectric properties were measured in the frequency range of 100 Hz to 10 MHz. The dielectric constant and dielectric loss were found to decrease with increasing frequency before reached a stable value. Increased saturation magnetization of NPs with high crystallinity and good homogeneity make these doped ferrites suitable for many applications.