Study of A-Site Disorder Dependent Structural, Magnetic, and Magnetocaloric Properties in La0.7-xSmxCa0.3MnO3 Manganites

We report studies on the magnetocaloric effect of samarium doped lanthanum manganites with different Sm-concentrations. Polycrystalline La0.7-xSmxCa0.30MnO3 (0 <= x <= 0.3) samples were prepared using the conventional solid-state reaction method with phase purity and structure confirmed using X-ray diffraction. Temperature dependent magnetization measurements and Arrott analysis reveal first order ferromagnetic transition in parent sample and second order ferromagnetic transition in doped sample with Curie temperature decreasing progressively with increasing Sm concentration from similar to 182 K for x = 0.05 to 109 K for x = 0.30. A large magnetic entropy change (similar to 1.75 J kg(-1) K-1 at 0.5 T) has been observed in La0.7Ca0.3MnO3 sample, and is greatly suppressed as a function of disorder caused by Sm doping. This is ascribed to the gradual loss of first-order ferromagnetic transition. This investigation suggests that La0.7-xSmxCa0.30MnO3 compounds can be used as a potential magnetic refrigerating material with wide range of temperature. (C) 2013 The Japan Society of Applied Physics