Magnetocaloric Properties of Zinc-Nickel Ferrites Around Room Temperature

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1-xNixFe2O4 (x= 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X-ray diffraction (XRD) and magnetization measurements were performed to study crystallographic structure and magnetic properties. For a magnetic field changing from 0 to 5 T, the corresponding isothermal entropy change was found to be near 1.4 J/kg K for both samples. The decreasing of Ni content from x= 0.4 to 0.3, enables to shift the Curie temperature of Zn1-xNixFe2O4 from 450 K toward (325 K). As main results, it was found that the relative cooling power (RCP) could be significantly enhanced by changing Ni concentration in Zn1-xNixFe2O4 (505 J/kg (for x= 0.3) and 670 J/kg (for x= 0.4)), which is considered as a recommended parameter for a wide temperature range in magnetic refrigeration application. Our finding should inspire and open new ways for the enhancement of the magnetocaloric effect in spinel ferrite-based materials.