Tunable Curie Temperature and Magnetocaloric Effect in Mg-Doped (La, Sr)MnO₃ Manganites

Abstract

In this paper we report on the structural, magnetic and magnetocaloric properties of La 0.67 Sr 0.33-x Mg x MnO 3 (x = 0, 0.05, 0.15 and 0.2) manganites synthesized by sol-gel method. The Mg-doping does not modify the crystal structure of the undoped manganite, but results in a slightly change of the lattice parameters. Both Curie temperature and saturation magnetization decrease with increasing Mg content. With a field change of 5 T, the maximum values of isothermal entropy change are found to be 2.49, 1.28, 1.37 and 1.30 J/kg·K for x = 0, 0.05, 0.15 and 0.2, respectively. The Mg-doped manganites exhibit stable MCE in a wide temperature range from ~50 K to ~300 K, which is important to the magnetic refrigeration.M 0018-9464 (c)lattice parameters are slightly modified by the Mg-doping. With the increasing Mg content, the Curie temperature and saturation magnetization decrease. The MCE peak is lowered and broadened by the Mg-doping. The maximum values of -ΔS T under a magnetic field change of 5 T are found to be 2.49, 1.28, 1.37 and 1.30 J/kg·K for x = 0, 0.05, 0.15 and 0.2, respectively.