Enhanced high temperature magnetic properties of ZnO − CoFe2O4 ceramic composite

Abstract

Multifunctional materials have been demonstrated to be suitable to several technological applications, particularly those that comprise both electrical and magnetic properties. Most of the technological applications requires operating temperatures above room temperature. In this study, we investigated the high temperature magnetic properties of 0.80ZnO 0.20CoFe2O4 ceramic composite, prepared by solid state reaction method from nanoparticulate powders of zinc oxide and cobalt ferrites. The T-dependence of the magnetic properties such as saturation magnetization, Ms, remanent magnetization, Mr, coercivity, Hc, and Curie temperature, Tc, were investigated in a broad range of temperatures varying from room temperature up to 870 K. We found that the Ms value of CoFe2O4 phase in the ceramic composite was ~1.5 times higher than those for pure CoFe2O4. Also the cubic magnetocrystalline anisotropy constant, K1, determined by the Law of Approach to saturation at several temperatures above room temperature was ~1.8 times higher than those for pure CoFe2O4. These enhanced magnetic properties were discussed in terms of the particle interactions induced by the thermal fluctuations, cation distribution, and exchange of ions between zinc oxide and cobalt ferrites phase in the composite.