SYNTHESIS AND CHARACTERIZATION OF La0,7Ca0,3 MnO3(AgX) mangnites

Abstract

This thesis presents results of an experimental investigations of structural and magnetoresistive characterization of a series of Polycrystalline Silver(Ag) doped lanthanum manganites, Lao,7Ca0.3MnO3(Ag X) ( x = 0.0, 0.1, 0.2, 0.3) with the perovskite structure. X-ray diffraction studies revealed that basic crystal structure of all the materials synthesized with different nominal compositions of Ca and Ag correspond to orthorhombic. Small variations in lattice parameters have been observed with change in the composition of Ca and Ag. The measurements of the variations of resistance with temperature in zero magnetic field showed M-I transition in all the samples synthesized in the present work and the M-I transition temperatures vary with compositions of Ca and Ag. The measurements of magnetoresistance of the sample synthesized with compositions La0.7Cao.3MnO3(Ag X) (x = 0.0, 0.1, 0.2, 0.3) in the magnetic field showed negative magnetoresistance and % MR vary with temperatures and compositions of Ca and Ag. The grain sizes of the samples have been estimated by SEM.