Magnetocaloric effect in nano- and polycrystalline manganites La0.5Ca0.5MnO3

Structure, magnetic and magnetocaloric properties of poly- and nanocrystalline La0.5Ca0.5MnO3 manganites prepared by the citrate sol-gel method are studied in a broad temperature range. The Arrott plots show that the phase transition is of the second order. The cooling efficiency of 93-97J/kg is found for the poly- and nanocrystalline samples. The relatively weaker magnetocaloric effect in nanocrystalline La0.5Ca0.5MnO3 is spread over temperature range almost three times broader than for the polycrystalline one. Charge ordering effects decay in manganites with grain sizes below 150 nm. (C) 2010 Elsevier B.V. All rights reserved.