Structural and magnetocaloric effect of Ln0.67Sr0.33MnO3 (Ln=La, Pr and Nd) nanoparticles

The Ln0.67Sr0.33MnO3 (Ln=La, Pr and Nd) nanoparticles were prepared by using the sol–gel method. The structural and magnetic properties of the samples were investigated in detail. The X-ray diffraction (XRD) analyses indicate that the La-doped sample crystalizes in rhombohedral perovskite structure and the Pr-doped and Nd-doped samples are mainly composed of orthorhombic perovskite structure phase. The Curie temperature and saturation magnetization are lowered and the phase transition is broadened by the Pr and Nd substitutions when comparing with the La-doped sample. All the samples exhibit significant magnetocaloric effects in a wide temperature range. Under a field change from 0 to 5 T, the maximum values of isothermal entropy change are found to be 2.49, 1.94 and 0.93 J/kg K for the samples with Ln=La, Pr and Nd, respectively, and the corresponding values of relative cooling power reach 225, 265 and 246 J/kg. The results suggest that those nanoparticles could be useful for magnetic refrigeration in a broad temperature range.