Magnetocaloric effect on strontium vacancies in polycrystalline La0.7Sr0.3-x square xMnO3

In this paper, we present the magnetocaloric effect of Sr vacancies in La0.7Sr0.3-x square xMnO3 compounds with x = 0 and 0.05. From the magnetic measurements as function of temperature and magnetic applied field, we have discovered a large magnetic entropy change (Delta S-M) at Curie temperature. Delta S-M is found to reduce for La0.7Sr0.25 square 0.05MnO3 sample (-1.78 J/kg K for x = 0 and 1.60 J/kg K for x = 0.05 under magnetic field change mu(0)Delta H = 2T). This reduction is accompanied by a decrease of the Curie temperature (T-C = 374 and 366 K for x = 0 and 0.05, respectively). These results show that these materials are potential candidates for magnetic refrigerants working in above room temperature. (C) 2007 Elsevier B.V. All rights reserved.