Structural, Magnetic, Magnetocaloric, and Critical Exponent Properties of La0.67Sr0.33MnO3 Powders Synthesized by Solid-State Reaction

Polycrystalline La0.67Sr0.33MnO3 (LSMO) powders were prepared by solid-state reaction, and their structural, magnetic, magnetocaloric, and critical exponent properties have been investigated. X-ray diffraction has shown that the sample is polycrystalline with a rhombohedral (R-3c) structure. Scanning electron microscopy has revealed that the surface of the sample is chemically homogeneous. The samples undergo a second-order magnetic transition from a ferromagnetic to a paramagnetic state with a Curie temperature of 361 K. The maximum entropy change is determined to be 274 J/kg K for a magnetic field change of 0–5 T. For the same applied field, the adiabatic temperature change and relative cooling power are found to be 1.75 K and 242 J/kg, respectively. These values are compared with those reported in the literature. It is concluded that large grain sizes are mandatory in order to obtain high magnetic refrigeration efficiency in LSMO-based compounds. Moreover, it is shown that the critical exponent values are in agreement with those of the long-range mean field model.