Study on synthesis and magnetocaloric effect of room temperature refrigeration materials La_(0.8-x)Sr_(0.2)Sm_xMnO_3 (0 ≤ x ≤ 0.2) by sol-gelmethod

摘要

In a lower magnetic field, perovskite manganese oxide has the prodigious potential of room temperature magnetic refrigeration because of its simple preparation, low cost and stable structure. In this paper, a series of polycrystalline nanomaterials La_(0.8-x)Sr_(0.2)Sm_xMnO_3(x = 0,0.05,0.1,0.15,0.2) were prepared by sol-gel method. The XRD patterns showed that the crystal structure of samples was rhombohedral and the surface morphology seen by SEM was ellipsoidal. The variation of magnetization with temperature and external magnetic field was measured by a superconducting quantum interferometer. By deducing and calculating, the ideal magnetic parameters are the maximum magnetic entropy change, Curie temperature and relative cooling power. Finally, It was found that when the doping amount of Sm~(3+) was in the range of 0.1 to 0.15, the Curie temperature was controlled in the range of 266 K to 303 K. Under the applied magnetic field of 5 T, the maximum magnetic entropy change was up to 4.03Jkg~(-1)K~(-1), and the maximum relative cooling power applicable to room temperature reached 295.31 J/kg, equivalent to 72.03% of the metal gadolinium (Gd) performance. These parameters show that present magnetic materials are prospective for applications.