Large magnetic entropy change near room temperature in La 0.7(Ca0.27Ag0.03)MnO3 perovskite
In this paper, the magnetic properties and magnetocaloric effect (MCE) of La0.7(Ca1−xAgx)0.3MnO3 (x = 0, 0.1, 0.2, 0.7, and 1) powder samples are reported. Our polycrystalline compounds were synthesized using the solid state reaction method at high temperature. Magnetization measurements versus temperature showed that all our samples exhibited a paramagnetic to ferromagnetic transition with decreasing temperature. The Curie temperature, TC, has been found to increase from ∼250 K for x = 0–270 K for x = 1. Ag doping weakens the first order phase transition, and at higher Ag doping, the phase transition is of second order. For the La0.7(Ca0.27Ag0.03)MnO3 composition, the maxima of the magnetic entropy changes from the applied magnetic field (ΔSM) at 2 and 5 T are about 4.5 and 7.75 J/kg K, respectively, at the Curie temperature of ∼263 K. The relative cooling power (RCP) values without hysteresis loss are about 102 and 271 J/kg for the applied fields of 2 and 5 T, respectively. Due to the large ΔSM, large RCP, and high Curie temperature, La0.7(Ca0.27Ag0.03)MnO3 is promising for application in potential magnetic refrigeration near room temperature.
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