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

We report detailed electrical, magnetic and thermoelectric studies on Bi-doped L0.7−xBixSr0.3MnO3 (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 (TMI) 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 TC is found to decrease with Bi-content. It is observed that MZFC and MFC 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.