Effect of Ca and Ba Doping on the Magnetotransport Properties of NdMnO3

Abstract

Mixed valence manganites of the type Nd0.7-xRxMnO3 where, R = divalent cation (Ca and Ba) have been synthesized using citrate pyrolysis process. It is interesting to see that the Ca and Ba doped NdMnO3 compounds have metal - insulating behavior but different TMI values at different magnetic field. Although the Ca and Ba ions have almost same ionic radii but different density. For Ca-doped NdMnO3 compound, a magnetoresistance as high as 79 % was observed at the insulator transition temperature Tp =102 K, while in Ba-doped NdMnO3 compound, lower magnetoresistance ~ 67% was observed at the metal insulator transition temperature Tp = 90 K. For both Ca & Ba doped NdMnO3 structural characterization shows same orthorhombic phase without impurities in the sample sintered at 900 °C, with the crystalline sizes in the nanometer scale. Grain size and morphology results show that the compounds have clear grain morphology and also nanoscale grain sizes.