The magnetocaloric properties of manganite oxides La0.7Sr0.25Na0.05Mn1 − xAlxO3 (LSNMAlx) synthesized by sol-gel method were studied in detail. X-ray diffraction analyses showed a single rhombohedral phase with the R3-c space group. The inhomogeneous magnetic compartment coupled with the core-shell behavior was used to explain the magnetic properties and the evolution of the paramagnetic-ferromagnetic transition of the materials. Using a phenomenological model, the maximum values of magnetic entropy change (ΔSmax) decreased from 4.92 J kg−1 K for La0.7Sr0.25Na0.05MnO3 to 3.84 J kg−1 K for La0.7Sr0.25Na0.05Mn0.95Al0.05O3 upon an applied magnetic field of μ0H = 5 T, indicating an excellent quality of our samples as compared to many manganite oxides. The high quality of our samples was also checked by the large relative cooling power (RCP) which provides a good performance for industrial technologies in refrigeration devices.

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