Abstract
Electron-doped (Ba1−x La x )MnO3 compounds were prepared for x=0−0.5. Measurements of X-ray diffraction (XRD) at room temperature and temperature variation of dc electrical resistivity down to 20 K were carried out. Samples with x=0.2–0.5 exhibit metal-insulator (M-I) transition. The maximum M-I transition temperature (T c) of 289 K was observed for 30% of La doping (x=0.3). XRD patterns of these samples (x=0.2−0.5) were analyzed using Rietveld refinement. These samples are found to be mostly in single-phase form with orthorhombic symmetry (space group Pbnm). We have found strong correlation between Mn-O-Mn bond angles and T c of M-I transition. The resistivity data below T c could be fitted to the expression ρ=ρ 1+ρ 2 T 2 and this shows that double exchange interaction plays a major role even in Mn4+-rich compound. Above T c the resistivity data were fitted to variable range hopping and small polaron models.
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