Large relative cooling power of Bi-doped La 0.8−x Bi x Sr 0.08 (Ca 0.55 Ba 0.45 ) 0.12 MnO 3 (x=0.0, 0.1 and 0.3) perovskites: Magnetic and magnetocaloric properties

Abstract We report magnetic and magnetocaloric properties of La 0.8−x Bi x Sr 0.08 (Ca 0.55 Ba 0.45 ) 0.12 MnO 3 ( x =0.0, 0.1 and 0.3) perovskite manganites. Polycrystalline samples have been synthesized in air by the sol gel method at a sintering temperature of 1150 °C. Powder X-ray diffraction data show that samples are phase pure and their cell parameters slightly decrease with increase in Bi content. Scanning electron micrographs show that the average particle size increases with increase in Bi content. The temperature dependent magnetization measurements show that the Curie temperatures decrease from 315 K ( x =0.0) to 140 K ( x =0.3) with increase in Bi content. The isothermal magnetization data is used to estimate the magnetic entropy changes (− Δ S M ) and their calculated values are 1.12 J kg −1 K −1 , 1.96 J kg −1 K −1 and 1.62 J kg −1 K −1 for x =0.0, 0.1 and 0.3 samples respectively under an applied magnetic field of 2.0 T. The corresponding values of relative cooling power (RCP) are 90 J kg −1 , 180 J kg −1 , 136 J kg −1 for x =0.0, 0.1 and 0.3 samples respectively. These results of magnetocaloric effect in our samples suggest that they are promising materials for the magnetic refrigeration applications.