Electrical and morphological properties of magnetocaloric nano ZnNi ferrite

Abstract

A series of Zn1–xNixFe2O4 nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples were single phase spinel cubic structure. The AC resistivity decreases by increasing the frequency from 1kHz to 10kHz. As the frequency of the applied field increases the hopping of charge carrier also increase, thereby decreasing the resistivity. A shift in dielectric maximum is observed toward higher temperature with increasing the Ni content from 536K to 560K at 1kHz. The HRTEM (high resolution TEM) images of four compositions have lattice spacing which confirms the crystalline nature of the samples. The surface morphology SEM of the sample consists of some grains with relatively homogenies distribution with an average size varying from 0.85 to 0.92μm. The values for entropy change in this work are still small but are significally higher than the values that have been reported for iron oxide nanoparticle. The magnetic entropy change was calculated from measurements of M (H, T) where H is the magnetic field and T is the temperature. The maximum value of entropy change (∆S) obtained near Curie temperature which makes these material candidates for magnetocaloric applications.