Tunable magnetocaloric effect near room temperature in La0.7-xPrxSr0.3MnO3 (0.02 ≤ x ≤ 0.30) manganites

We have systematically investigated the compositional dependence of the magnetic and magnetocaloric properties of La0.7-xPrxSr0.3MnO3 (LPSMO). Polycrystalline samples of LPSMO with 0.02 <= x <= 0.30 were prepared by a standard solid-state reaction method with phase purity and structure confirmed using x-ray diffraction. Temperature dependent magnetization measurements and Arrott analysis reveal second order ferromagnetic transitions in each sample with Curie temperature decreasing progressively with increasing Pr content from similar to 350 K for x 0.02 to similar to 295 K for x 0.30. Magnetic entropy change (Delta S-M) was calculated by applying the thermodynamic Maxwell equation to a series of isothermal field dependent magnetization curves. In the sample with x 0.30, the maximum value of -Delta S-M reaches similar to 2.08 J/kg K at 295 K for a field change of 1.5 T. Reduced Pr content corresponds to larger values of entropy change, reaching -Delta S-M similar to 2.79 J/kg K for the x-0.02 doping. The refrigeration capacity for each composition reached sizable values of 33-48 J/kg for a small applied field of 1.5 T. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3698346]