Structural and transport properties of composite of La0.8Sr0.2MnO3 and BaTiO3 materials

We studied the effect of BaTiO3 phase on the structural, vibrational, and electrical properties of La0.8Sr0.2MnO3. The parent samples of La0.8Sr0.2MnO3, BaTiO3 and their composite (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 were synthesized by solid-state reaction route. Structural study using X-ray diffraction (XRD) for La0.8Sr0.2MnO3 phase revealed a rhombohedrally distorted (space group R3c) structure, while BaTiO3 compound was found to have crystallized in tetragonal structure (space group P4mm). The XRD results were verified using Rietveld refinement. The composite sample (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 display the presence of both of La0.8Sr0.2MnO3 and BaTiO3 phases. The addition of insulating BaTiO3 phase in the ferromagnetic metallic phase of La0.8Sr0.2MnO3 which exhibits well-characterized metal-to-insulator transition in the vicinity of 350 K enhances the resistivity and shifts the metal–insulator transition temperature TMI towards lower temperature. Further, with the application of magnetic field, resistivity of the composite sample is found to decrease and TMI in composite sample is observed to shift towards higher temperature. The magnetoresistance (MR) of composite sample (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 decreases monotonously in 200–300 K regime under magnetic field of 8 T. The analysis of electrical resistivity data in the metallic region (T < TMI) suggests that the electron–electron scattering is predominant in this region, whereas the insulating region (T > TMI) is well described using Small polaron hopping (SPH) and Mott's variable range hopping (VRH) models.