Effect of elaborating method on magnetocaloric properties of La0.7Ca0.2Ba0.1MnO3 manganite

Abstract

In this paper, we investigate the effect of elaborating method on the magnetocaloric properties of La0.7Ca0.2 Ba0.1Mn03 manganite powder. Our samples have been synthesised using the solid state reaction (sample 1) and high energy ball milling method (sample 2). X-ray diffraction and magnetization measurements were performed to investigate the crystallographic structure and magnetocaloric properties. An orthorhombic structure with Pbnm space group is deduced from the refinement of the XRD patterns for both samples. A second-order magnetic phase transition from ferromagnetic to paramagnetic state is observed and confirmed in terms of Landau theory and universal theory. The Curie temperature TC is found to be 297 K for sample 1 and 230 K for sample 2. The maximum of the magnetic entropy change ΔSMMax at μ0H = 3 T decreases from 2.5 J/kg K−1 for sample 1–2.25 J/kg K−1 for sample 2, while, the relative cooling power RCP increases from 132.5 J/Kg for sample 1–142.8 J/Kg for sample 2. The comparison of the values reported in the reference Gd material underlines that the proposed manganite material has substantial advantages for magnetic refrigeration. Field dependences of ΔSMMax and RCP can be expressed by the power laws, ΔSMMax≈a(μ0H)n and RCP ≈ b (μ0H)m, where a and b are coefficients, n and m are the field exponents, respectively.