Current Applied Physics, Vol.19, No.4, 424-435, 2019
Effect of Co-doping on structural, magnetic and magnetocaloric properties of La0.67Ca0.13Ba0.2Mn1-xCoxO3 (x=0, 0.02, 0.04, 0.06, 0.08, 0.1) manganites
The bulk polycrystalline samples of La0.67Ca0.13Ba0.2Mn1-xCoxO3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) have been prepared by conventional solid-state reaction method. X-ray powder diffraction shows that all samples crystallize in the rhombohedral structure with R (3) over barc space group symmetry. The ratio of Co3+/Co4+ gradually increases with increasing Co doping composition, which was determined by XPS analysis. The temperature and applied magnetic field dependence of magnetization were carried out. All samples exhibit a FM-PM transition at the Curie temperature T-C, which decreases from 312 K to 223 K with increasing Co composition. Critical analysis shows that the estimated critical exponents beta, gamma and delta are in between the theoretically predicted values for 3D-Heisenberg and mean-field theory models for all samples. The magnetocaloric effect has been calculated from isothermal magnetization curve at various temperatures near T-C. The maximum magnetic entropy changes -Delta S-max under applied magnetic field of 1.6 T were found to be 3.18 J kg(-1) K-1, 2.47 J kg(-1) K-1 and 2.68 J kg(-1) K-1 respectively for x = 0, 0.02 and 0.04 composition, which will be an interesting compound for application materials working as magnetic refrigerants near room temperature.