Structural and transport properties of composite of La_0.8Sr_0.2MnO₃ and BaTiO₃ materials

We studied the effect of BaTiO₃ phase on the structural, vibrational, and electrical properties of La_0.8Sr_0.2MnO₃. The parent samples of La_0.8Sr_0.2MnO₃, BaTiO₃ and their composite (0.85) La_0.8Sr_0.2MnO₃ + (0.15) BaTiO₃ were synthesized by solid-state reaction route. Structural study using X-ray diffraction (XRD) for La_0.8Sr_0.2MnO₃ 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) La_0.8Sr_0.2MnO₃ + (0.15) BaTiO₃ display the presence of both of La_0.8Sr_0.2MnO₃ and BaTiO₃ phases. The addition of insulating BaTiO₃ phase in the ferromagnetic metallic phase of La_0.8Sr_0.2MnO₃ which exhibits well-characterized metal-to-insulator transition in the vicinity of 350 K enhances the resistivity and shifts the metal–insulator transition temperature T_MI towards lower temperature. Further, with the application of magnetic field, resistivity of the composite sample is found to decrease and T_MI in composite sample is observed to shift towards higher temperature. The magnetoresistance (MR) of composite sample (0.85) La_0.8Sr_0.2MnO₃ + (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 < T_MI) suggests that the electron–electron scattering is predominant in this region, whereas the insulating region (T > T_MI) is well described using Small polaron hopping (SPH) and Mott's variable range hopping (VRH) models.