Structural, Magnetic, and Magnetocaloric Properties of La0.5M0.1Sr0.4MnO3 (M=Bi, Eu, Gd, and Dy) Perovskite Manganites

Structural, magnetic, and magnetocaloric properties of La0.5M0.1Sr0.4MnO3 (M=Bi, Eu, Gd, and Dy) powder samples, synthesized using the solid-state reaction at high temperature, have been experimentally investigated. X-ray diffraction analysis using the Rietveld refinement show that La0.5Bi0.1Sr0.4MnO3 sample is single phase and crystallizes in the rhombohedral system with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$R\overline{3}c$\end{document} space group whereas a mixture of orthorhombic (Pbnm) and rhombohedral (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$R\overline{3}c$\end{document}) phases is observed for M=Eu, Gd, and Dy compounds. The Curie temperature, TC, shifts to lower temperature with decreasing the average A-site ionic radius 〈rA〉, which is consistent with large cationic disorder. Arrott plots show that all our samples exhibit a second order magnetic phase transition. From the measured magnetization data of La0.5M0.1Sr0.4MnO3 (M=Bi, Eu, Gd, and Dy) samples as a function of magnetic applied field, the associated magnetic entropy change |ΔSM| has been determined. In the vicinity of TC, |ΔSM| reached, in a magnetic applied field of 1 T, maximum values of 0.98 J/kg K, 1.01 J/kg K, 0.81 J/kg K, and 0.77 J/kg K for M=Bi, Eu, Gd, and Dy, respectively.