Unveiling high resistivity mechanism in (0.8-x)BaTiO₃-0.2BiScO₃-x(Bi_0.5Li_0.5)TiO₃ ceramics with good dielectric temperature-stability

Focusing on the high resistivity together with low intrinsic conduction in BaTiO₃–BiMeO₃ materials, it can contribute to the development of reliable high-temperature capacitor materials. In this work, x(Bi_0·5Li_0.5)TiO₃-(0.8-x)BaTiO₃-0.2BiScO₃ (where x ranges from 0 to 0.2) ceramics were fabricated by a solid reaction method. The temperature stability of dielectric permittivity and resistance are improved significantly by the introduce of (Bi_0·5Li_0.5)TiO₃ (referred to as BL) compared to BaTiO₃–BiMeO₃. The composition discrepancy due to chemical inhomogeneity can be determined by SEM and EDS mapping although XRD exhibit a single perovskite phase. The characteristics of distinct conductivity behaviors in micro-regions was measured by kelvin probe force microscopy (KPFM). The non-stoichiometry gives rise to two kinds of defects for charge compensation: an ionic compensation and oxygen-vacancy compensation in different grains. The increase of the hopping activation energy of charged carries enhances the high-temperature resistance of the system. The sample of x = 0.15 shows very good temperature stability of dielectric permittivity in the temperature range from 200 °C to 400 °C, and that of x = 0.1 exhibits the highest resistivity of 3.6 MΩ cm at 570 °C. The proposed method gives an efficient strategy for improving the dielectric temperature stability and insulation by the special defect compensation in the perovskite oxides. © 2024 Elsevier Ltd and Techna Group S.r.l.