Effect of Zn on the Magnetic and Magnetocaloric Properties of (0.95)La0.7Ca0.3MnO3/(0.05)Mn1−x Zn x Fe2O4 Composites

Abstract

We report the structural, magnetic, and magnetocaloric properties of (0.95)La0.7Ca0.3MnO3/(0.05)Mn1−x Zn x Fe2O4 (x = 0.0, 0.1, 0.3, 0.5) composites. Polycrystalline samples of the composite material were prepared using the solid-state reaction method. The phase purity and structure of the samples were confirmed using the X-ray powder diffraction (XRD) method. Scanning electron microscope (SEM) studies of the samples reveal that Mn1−x Zn x Fe2O4 is mainly distributed at the surface and grain boundaries of the perovskite matrix La0.7Ca0.3MnO3. The variation of magnetization (M) as a function of temperature and applied magnetic field was investigated. The M-T data plots indicate a paramagnetic to ferromagnetic transition upon cooling in all samples. The magnetic entropy change was also studied through the examination of measured magnetic isotherms, M (H, T) near Curie temperature T C . A magnetocaloric effect has been estimated in terms of isothermal magnetic entropy change. A maximum entropy change value of 1.72 J/kg K was recorded for a magnetic field change of 3 T with a relative cooling power (RCP) value of 177 J/kg for the (0.95)La0.7Ca0.3MnO3/(0.05)MnFe2O4 composite sample.