Magnetocaloric properties of (La1-xPrx)0.85K0.15MnO3 (x=0.0, 0.1, 0.3 and 0.5) perovskite manganites

In this study, we have investigated the effect of Pr on the structural, magnetic and magnetocaloric properties of La1-xPrx)(0.85)K0.15MnO3 (x=0.0, 0.1, 0.3 and 0.5) samples synthesized by sol-gel technique. The XRD patterns of samples for x=0.0 and 0.1 are indexed to rhombohedral structure with hexagonal setting (space group R (3) over barc) while the samples for x=0.3 and 0.5 crystallized in the orthorhombic structure with space group Pbnm. Magnetization measurements versus temperature in a magnetic field of 250 Oe indicate that all samples show a ferromagnetic to paramagnetic transition with increasing temperature. The Curie temperature, T-C, decreases with increasing Pr3+ concentration from 238 K for x=0.0-158 IC for x=0.5. We determined the magnetic entropy changes of the samples from M(H) isotherms that were measured around T-C. The values of maximum magnetic entropy change were found to be 4.63, 5.22, 2.80 and 2.30 J kg(-1) K-1 for x=0.0, 0.1, 0.3 and 0.5 for a field change of 2 T, respectively. For LPKM1 sample, we have also calculated the value of adiabatic temperature change as 3.11 K from the heat capacity and isothermal magnetization measurements under magnetic field of 2 T.