Magnetocaloric Effect in La_0.67Ba_0.33Mn_0.95Ni_0.05O₃ Manganite Near Room Temperature

We report the structural, magnetic, and magnetocaloric properties of La_0.67Ba_0.33Mn_0.95Ni_0.05O₃ (LBMNO) manganite, synthesized by sol-gel method. X-ray diffraction (XRD) analysis using Rietveld refinement showed that this sample crystallizes in the rhombohedral structure with R$\overline{3}$c space group. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were used to confirm the structure formation of the LBMNO material. The temperature dependent magnetization data revealed a transition from ferromagnetic (FM) to paramagnetic (PM) phase at $T_C=$ 308 K. Using Arrott plots, it was found that the transition is of a second order. From the measured magnetization data as a function of magnetic applied field, the magnetic entropy change (−ΔS_M) and the relative cooling power RCP have been determined. In the vicinity of $T_C$ (−ΔS_M) reached a maximum value of 2.15 J kg^− 1 K^− 1 and a large RCP value of about 299 J kg^− 1 under 5 T^− 1. This magnetocaloric effect has been analyzed by considering the Landau theory of magnetic phase transition. Consequently, our sample can be considered a promising material in room-temperature magnetic refrigeration.