Magneto Transport Anomaly of Bismuth Substituted (La, Na) MnO₃

The structural and magneto-transport properties of polycrystalline La_0.85–xBi_xNa_0.15MnO₃, (x = 0, 0.05, 0.1, 0.2) manganites are reported. The polycrystalline samples were prepared using solid-state synthesis route. Rietveld refinement of X-ray data conclude the samples crystallized in a rhombohedrally distorted structure belonging to R3 ¯ C space group with no prominent structural changes upon bismuth substitution. Scanning electron microscopy has revealed improvement of microstructure from loosely bound system to densely packed array of grain. Resistivity measurements disclose metal–insulator transition for all the samples. A double metal–insulator transition is observed in samples with low concentrations (x = 0.05, 0.1). All samples have shown second-order magnetic phase transition.