Crystal structure, magnetic and magnetocaloric properties of aluminum-doped La0.6Sr0.4MnO3 perovskites

In this paper, we report on the structural, magnetic and magnetocaloric properties of a series of nanocrystallines La0.6Sr0.4Mn1−xAlxO3 (0 ≤ x ≤ 0.2) which were prepared by the sol–gel method. The X-ray powder diffraction showed that all our synthesized samples were of a single phase and have crystallized in the hexagonal symmetry with R3¯c\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{R}}\bar{3}{\text{c}} $$\end{document} space group. Magnetic measurements showed that the sample exhibits a ferromagnetic-to-paramagnetic phase transition at a Curie temperature close to 206 K. The maximum value of the magnetic entropy change ΔSMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left| {\Delta S_{\text{M}}^{ \hbox{max} } } \right| $$\end{document} was found to be 1.09 J kg−1 K−1 for an applied magnetic field of 5T. At this value of magnetic field, the relative cooling power was 141 J kg−1. Our result on magnetocaloric properties suggests that La0.6Sr0.4Mn1−xAlxO3 nanopowder with (0 ≤ x ≤ 0.2) is attractive as a potential refrigerant for high-temperature magnetic refrigeration.