Structural, magnetic and magnetocaloric properties of K-doped Pr0.8Na0.2-xKxMnO3 manganites

In the present study we report the effect of A-site substitution by Potassium on the structural, magnetic and magnetocaloric properties in Pr0.8Na0.2-xKxMnO3 (0 <= x <= 0.15) samples synthesized using the solid state reaction at high temperatures. The Rietveld refinement of the X-ray powder diffraction shows that all our samples crystallize in the orthorhombic symmetry with Pbnm space group. The surface morphology of these samples was carried out using scanning electron microscopy (SEM). Magnetization measurements versus temperature in a magnetic applied field of 0.05 T indicate that K doping leads to a paramagnetic-ferromagnetic transition with a Curie temperature T-C increasing from 117 K for x = 0.05 to 132 K for x = 0.15. The maximum of the magnetic entropy change vertical bar Delta S-M(Max)vertical bar under a magnetic field of 5 T is found to be 3.20, 3.44, 3.32, and 3.30 Jkg(-1) K-1 for x = 0, 0.05, 0.1 and 0.15, respectively. Large relative cooling power (RCP) value of 355.6 Jkg(-1) is obtained for Pr0.8Na0.2MnO3 compound, at a field change of 5 T. This relatively large value associated to a Curie temperature of 90 K make the present compound a promising candidate for magnetic refrigeration at low temperatures. (C) 2015 Elsevier B.V. All rights reserved.