Structural properties and electrical resistivity behaviour of La1−x KxMnO3 (x = 0.1, 0.125 and 0.15) manganites

We report structural features and electrical conductivity behaviour of the potassium doped LaMnO3 perovskite. La1−x KxMnO3 perovskites (x = 0.1, 0.125 and 0.150) have been prepared by the solid-state reaction method and characterised by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and dc electrical resistivity. The Rietveld refinements of X-ray diffraction patterns identify rhombohedrally-distorted structure with space group image. The resistivity of all the samples exhibit metal–insulator transition, at about 244, 259, and 280 K, respectively which enhances on application of 5 T field. At low temperatures (≤30 K), resistivity shows an upturn which on application of magnetic field ≈ 5 T suppresses. The metallic resistivity (H = 0, 5 T) behaviour is analysed in terms of electron–phonon, electron–electron and electron–spin fluctuation scattering. The small polaron conduction is adequate to explain semiconducting resistivity (H = 0, 5 T). The resistivity upturn (H = 0) is explained by considering Coulomb interaction and Kondo-like spin dependent scattering. For H = 5 T, Coulomb interaction between carriers strongly enhanced by disorder is sufficient to explain the resistivity upturn.