Effect of Pr-substitution on the structural, magnetic and magnetocaloric properties of (La1-xPrx)0.67Pb0.33MnO3 (0.0 ≤ x ≤ 0.3) manganites

Abstract

The effects of the substitution of La3+ by smaller rare-earth ion Pr3+ on the structural, magnetic and magnetocaloric properties of (La1-xPrx)0.67Pb0.33MnO3 (0.0 ≤ x ≤ 0.3) compounds prepared by sol-gel method have been investigated. X-ray diffraction (XRD) showed that samples crystallize in the orthorhombic perovskite structure with Pnma space group. Thermomagnetic measurements indicate that all the samples exhibit a magnetic transition from ferromagnetic to paramagnetic phase with increasing temperature. Curie temperature, TC, systematically decreases from 358 K for x = 0.0 to 330 K for x = 0.3 as the average ionic radius of the A-site elements. The magnetic entropy change, ΔSM, was calculated from the isothermal magnetization measurements as a function of applied magnetic field at several temperatures around TC. The maximum of magnetic entropy change was found to be 4.43, 3.08, 3.33 and 2.97 Jkg−1K−1 for x = 0.0, 0.1, 0.2 and 0.3, respectively, for a magnetic field change of 4.8 T. The field dependence of the magnetic entropy change is also analyzed and can be expressed by a power law ΔSmmax=a(μ0H)n, where the magnetic-ordering parameter is n = 0.59, 0.62, 0.62 and 0.65 at 4.8T applied magnetic field for x = 0.0, 0.1, 0.2 and 0.3 samples, respectively. Arrott plots and universal behavior of the scaled entropy change curves show that all samples display a second order magnetic phase transition.