Colossal permittivity (Nb, Mg) co-doped BaTiO3 ceramics with excellent temperature stability and high insulation resistivity

Abstract

High performance colossal permittivity ceramic materials are indispensable for the development of electronic devices. In this work, Mg and Nb co-doping BaTiO3 ceramics were prepared by solid-state reaction under reducing atmosphere. The polarization mechanism, dielectric properties and insulation mechanism were investigated. The defect dipoles ([MgTi″−VO••]× and [MgTi″−2NbTi•]×) could be formed inside co-doping BaTiO3 ceramics with various content of MgO, which is the source of colossal permittivity. Appropriate MgO content doping is favorable to enhance short-range hopping, thus improve grain resistance, grain boundary resistance and grain boundary activation energy. The 1.0 at% MgO modified BaTiO3-0.01Nb2O5 ceramics possess excellent performance at room temperature with colossal dielectric constant (ԑr = 4.5 × 104), low dielectric loss (tanδ<0.018), and high insulation resistivity (ρv = 6.52 × 1011 Ω cm). Meanwhile, good temperature stability is obtained in 1.0 at% MgO modified BaTiO3-0.01Nb2O5 ceramics, which satisfies the Electronic Industries Association (EIA) X8R (−55–150 °C, △εr/ε25≤ ±15%) specification. This study suggests that the defect-dipoles related polarization mechanism can be used to design the colossal permittivity BaTiO3-based ceramics.