Magnetoresistance studies on barium doped nanocrystalline manganite

An energetically attractive, simple, fast and a novel low temperature (300 °C) solution combustion route for the synthesis of crystalline and homogeneous nanoparticles of lanthanum barium manganese oxide La_0.9Ba_0.1MnO_3+δ (LBMO) is reported. Formation and homogeneity of the solid solutions have been confirmed by powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDS) respectively. The Rietveld analysis shows both as-formed as well as calcined samples are in cubic phase with space group pm3m. The microstructure and agglomerated particle size of the compounds are examined by scanning electron microscope. Infrared spectroscopy revealed that both MnOMn bending mode and MnO stretching mode are influenced by calcination temperature. The magnetoresistance measurement on sintered LBMO pellet exhibits a broad metal–insulator transition (T_M-I) at around 228 K. At 1 T applied magnetic field, LBMO shows magnetoresistance (MR) of 10%, whereas for 4 and 7 T, the negative magnetoresistance values are in the range 51 and 59% respectively at T_M-I. The experimental resistivity data of the present investigation are fitted to a simple empirical equation in order to understand conduction mechanism in this compound.