The structural, magnetic and magnetocaloric properties of Ba doped La manganites

The structural, magnetic and magnetocaloric properties of barium doped lanthanum manganites La1-xBaxMnO3 with x = 0.1, 0.2 and 0.3 compositions were investigated. The X-ray powder diffraction results show that all samples crystallize in the rhombohedral R-3c space group. The substitution of La3+ by the larger Ba+2 ions induces an increase of the unit cell volume when the doping level increases from 10% to 20%. On the contrary a further increase of Ba doping at 30% causes a decrease in the volume of unit cell. All samples exhibit a ferromagnetic to paramagnetic transition. Transition temperature increases from 181 K to 319 K with increasing doping level. Above transition temperature the paramagnetic behavior of the samples is well described by the Curie - Weiss law. Arrott-Belov plots show that all samples follow the behavior expected for a conventional second order transition. The magnetic entropy change and relative cooling power have been determined. vertical bar Delta S-M(max)vertical bar observed in the vicinity of transition temperature increases monotonically from 1.51 Jkg(-1)K(-1) for x = 0.1 to 2.61 Jkg(-1)K(-1) for x = 0.3 for a field change of 2 T. The observed temperature dependence of Delta S-M is explained reasonably well by the Landau theory of second order phase transition. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim