INTERNATIONAL JOURNAL OF MODERN PHYSICS B, cilt.21, sa.1, ss.43-53, 2007 (SCI-Expanded)
La-0:67 Ca-0:33 MnO3 samples prepared by polymeric precursor route method are investigated using the thermogravimetric, differential thermal analysis, X-ray powder diffraction, scanning electron microscope, infrared spectroscopy and magnetic measurements. The unit cell parameters and grain size for all the samples are re fined using X-ray diffraction and scanning electron microscope. It is observed that the IR bands at about 400 cm 1 is are most likely due to Mn - O - Mn bending mode and the band at 600 cm 1 is the result of the in plane Mn O stretching mode. Magnetization measurements indicated that the Curie temperature increases from 241.3 K for the sample sintered at 600 degrees C to 268.86 K for the sample sintered at 1000 degrees C as a function of sintering temperature. The magnetic entropy change reaches the maximum value of about 4 : 8 J/kg center dot K for the sample sintered at 1150 degrees C at an applied field of 1 T.