Magnetocaloric effect in manganite perovskites La0.77Sr0.23Mn1-xCuxO3(0.1 ≤ x ≤ 0.3)

The magnetocaloric properties of the polycrystalline manganites perovskite La0.77Sr0.23Mn1-xCuxO3 with 0.1 <= x <= 0.3 have been investigated. The maximum magnetic entropy change. Delta S-M(max), of Cu doped manganites increases gradually with increasing applied magnetic field. The maximum values of magnetic entropy changes of Cu doped manganites samples is found to decrease with the further increasing of Cu concentration in the romboherderal phase (x <= 0.2). However, with increasing Cu contents (x >= 0.3) structure transformed into orthorhombic phase and, hence Delta S-M(max), start to increase again with increasing Cu doped concentration. It was found that the maximum value of the magnetic entropy change increases near their respective T-C from 3.09 J/kg K at 0.1 T and reached highest value of 4.41 J/kg K at 1T for compound with x = 0.1. Delta S-M(max) in La0.77Sr0.23Mn0.9Cu0.1O3 at 1 T is found to be 26% higher than that known for the prototype magnetic refrigerant with pure Gd. The relative cooling power (RCP) of La0.77Sr0.23Mn1-xCuxO3 is nearly 60% of pure Gd. Thus, due to the high Delta S-M(max) and RCP values, sample with x = 0.1 (at mu(0)Delta H = 1T) is the most promising compound to be used as magnetomechnical materials. (c) 2008 Elsevier Ltd. All rights reserved.