Magnetic properties of A- and B-site cation doped La0.65Ca0.35MnO3 manganites

The La0.65Ca0.35MnO3, La0.65Ca0.30Pb0.05MnO3 and La0.65Ca0.30Pb0.05Mn0.9Cu0.1O3 compounds, prepared by the sol-gel method and sintered in air at 1100 degrees C for 24 h, have been investigated by Magnetic Properties Measurements System (MPMS) to explore the effects of A- and B-site cation doping. From the measurements, the Curie temperatures (T-C) and the isothermal magnetic entropy changes (-Delta S-M) were determined. The Curie temperature of La(0.6)5Ca(0.35)MnO(3) compound was found to be 273 K. The Curie temperature increases to 286 K for the La0.65Ca0.30Pb0.05MnO3 compound due to the substitution of Ca by a small amount of Pb. However, replacing 10% of Mn with Cu (La0.65Ca0.30Pb0.05Mn0.9Cu0.1O3) leads to a reduction in the Curie temperature to 223K. For the field change of 1 T, while the maximum magnetic entropy change for the sample La0.65Ca0.35MnO3 was found to be 4.1 J/kg K it decreases down to 2.6 J/kg K and 3.2 J/kg K for the La0.65Ca0.30Pb0.05MnO3 and La0.65Ca0.30Pb0.55Mn0.9Cu0.1O3 samples, respectively. (C) 2010 Elsevier B.V. All rights reserved.