Effects of partial Mn-substitution on magnetic and magnetocaloric properties in Pr0.7Ca0.3Mn0.95X0.05O3 (Cr, Ni, Co and Fe) manganites

Structural, magnetic and magnetocaloric properties of Pr0.7Ca0.3Mn0.95X0.05O3(X = Cr, Ni, Co and Fe) ceramics have been investigated by X-ray diffraction (XRD) and magnetic measurements. Powder samples have been elaborated using the solid state reaction method at high temperature. The Rietveld analysis of the powder X-ray diffraction shows that the samples crystallize in the orthorhombic structure with Prima space group. Magnetic measurements show that all our materials exhibit a paramagnetic-ferromagnetic transition with decreasing temperature. The Arrott plots of ours materials reveal the occurrence of a second-order phase transition. The maximum values of magnetic entropy change vertical bar Delta S-M(max)vertical bar are 2.92, 2.96, 3.1, and 2.38 J kg(-1) K-1 and the relative cooling power (RCP) values are 405.8, 378.2, 352.2 and 337.4 J kg(-1) for a magnetic-field change from 0 to 5 T for Cr, Ni, Co and Fe respectively. The large RCP found in our substituted samples will be interesting for magnetic refrigeration over a wide temperature range similar to 130 K around its paramagnetic to ferromagnetic transition temperature. With the scaling laws of Delta S-M, the experimental Delta S-M collapse onto a universal curve for several ceramics, where an average curve is obtained. With the phenomenological universal curve, the experimental Delta S-M are well predicted for all materials. (C) 2014 Elsevier B.V. All rights reserved.