Large Magnetocaloric Effect of Sm3+-Doped La0.7Sr0.3–xSmxMn0.95Ni0.05O3(x = 0, 0.05, 0.10, 0.15) Manganites Near Room Temperature

A La 0.7 Sr 0.3− x Sm x Mn 0.95 Ni 0.05 O 3 ( x = 0, 0.05, 0.10, 0.15) series of manganites were synthesized by the Pechini sol–gel method. The changes in structure and magnetic properties caused by the substitution of Sr 2+ by Sm 3+ were systematically investigated. The results of Rietveld refinement using GSAS (General Structure Analysis System) software showed that the samples had a rhombohedral structure before and after the substitution, but the cell volume increased. In addition, the Curie temperature ( T C ) of the samples gradually decreased with increased doping, and the magnetic entropy change ( Δ S M ) showed the same trend. This can be attributed to the weakening of the ferromagnetic coupling between Mn 4+ and Mn 3+ . For the doped sample with x = 0.05, the T C was 300 K, and the maximum magnetic entropy change ( - Δ S M max ) reached 4.59 J kg −1 K −1 at an applied magnetic field of 5 T. The relative cooling power (RCP) also reached 297.39 J kg −1 , which is certainly promising for meeting the need for room-temperature magnetic refrigeration. Graphical Abstract