Electrical, thermal and magnetic properties of Bi doped La0.7−xBixSr0.3MnO3 manganites.

We report detailed electrical, magnetic and thermoelectric studies on Bi-doped L 0.7− x Bi x Sr 0.3 MnO 3 (0 ⩽ x ⩽ 0.25) manganites. The XRD patterns and Rietveld analysis show that the studied materials are single phased. All the compounds, exhibit the expected metal–insulator transition and a decrease in the characteristic metal–insulator transition temperature ( T MI ) is observed to decrease with increase in Bi-content. Low temperature resistivity data indicates that grain boundaries and electron–electron scattering processes contribute vital role in the conduction process. Magnetic studies also show that the Curie temperature T C is found to decrease with Bi-content. It is observed that M ZFC and M FC curves become more manifested as Bi-content is increased which indicates an increase in magnetic frustration arising due to bending of Mn–O–Mn bond. High temperature analysis on the electrical resistivity and thermoelectric power data indicates that small polaron hopping (SPH) model is valid for all the samples. [ABSTRACT FROM AUTHOR]