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

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 ([Mg ''(Ti)-V-O(center dot center dot)](x) and [Mg ''(Ti)-2Nb(Ti)(center dot)](x)) 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 BaTiO3-0.01Nb(2)O(5) ceramics possess excellent performance at room temperature with colossal dielectric constant (epsilon(r) = 4.5 x 10(4)), low dielectric loss (tan delta<0.018), and high insulation resistivity (rho(v) = 6.52 x 10(11) Omega cm). Meanwhile, good temperature stability is obtained in 1.0 at% MgO modified BaTiO3-0.01Nb(2)O(5) ceramics, which satisfies the Electronic Industries Association (EIA) X8R (-55-150 degrees C, Delta epsilon(r)/epsilon(25)<= +/- 15%) specification. This study suggests that the defect-dipoles related polarization mechanism can be used to design the colossal permittivity BaTiO3-based ceramics.