Study on the Effect of Vacancy Doping on the Magnetocaloric Effect of La0.65−xCa0.35MnO3 (0 ≤ x ≤ 0.15)

A series of vacant doping samples of La0.65−xCa0.35MnO3 (x = 0, 0.05, 0.10, 0.15) were prepared by sol-gel method. XRD analysis results show that all samples are a single-phase perovskite structure; XRD refinement demonstrates that La0.50Ca0.35MnO3 is a single phase with the space group Pbnm. When x = 0.15, the variation of magnetization versus temperature in a magnetic applied field of the sample indicates that La0.5Ca0.35MnO3 is converted from a ferromagnetic phase to a paramagnetic phase. The Curie temperature (Tc) of the sample increases with the concentration of vacancy doping. The value of Tc increases from 209.5 to 242.1 K when x increases from 0 to 0.15. The Arrott plot indicates that the phase transition occurring in the sample is a secondary phase transition. When x = 0.15, the Curie temperature of the sample reaches 242.1 K; when the magnetic field variation is equal to 5 T, the maximum magnetic entropy changes (− ΔSM) of the sample become 1.77 J kg−1 K−1 and the relative cooling capacity (RCP) is 95.58 J•kg−1.