Structural, magnetic and magnetocaloric properties of K-doped Pr sub(0.8)Na sub(0.2-x)K sub(x)MnO sub(3) manganites

In the present study we report the effect of A-site substitution by Potassium on the structural, magnetic and magnetocaloric properties in Pr sub(0.8)Na sub(0.2-x)K sub(x)MnO sub(3) (0 [< or =] x [< or =] 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 sub(C) increasing from 117 K for x = 0.05 to 132 K for x = 0.15. The maximum of the magnetic entropy change (ProQuest: Formulae and/or non-USASCII text omitted) under a magnetic field of 5 T is found to be 3.20, 3.44, 3.32, and 3.30 Jkg super(-1) K super(-1) for x = 0, 0.05, 0.1 and 0.15, respectively. Large relative cooling power (RCP) value of 355.6 Jkg super(-1) is obtained for Pr sub(0.8)Na sub(0.2)MnO sub(3) 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.