Improved dielectric properties and anti-reducing mechanism of Er/Mg Co-doped BaTiO3-based ceramics produced in reducing atmosphere

BaTiO 3 -1.6MnO 2 - x Er 2 O 3 ceramics (abbreviated as BMT- x Er) and BaTiO 3 -1.6MnO 2 -3Er 2 O 3 - x MgO ceramics (abbreviated as BEMT- x Mg) were prepared under a reducing atmosphere by solid-state synthesis method in this work. The effects of Er/Mg co-doping on phase transformation, microstructure, dielectric properties, and defect were systematically investigated. Research shows that Er-doping reduces the Curie temperature and increases the dielectric constant of BaTiO 3 ceramics at low temperatures. Mg-doping refines the grain size and makes the grain size distribution more uniform, which is an important reason for the enhanced bias stability. The substitution of Mg at the B-site generates additional oxygen vacancies which capture free electrons and simultaneously forms defect dipoles. The anti-reducing properties are improved by reducing the carrier concentration. The synergistic effect of co-doping forms defect dipoles such as [ Mg Ti ″ ‐ 2 Er Ba ∙ ] , [ Mg Ti ″ ‐ V O ∙ ∙ ] and [ 2 Er Ti ′ ‐ V O ∙ ∙ ] to enhance dielectric relaxation behavior which is considered to be the reason for the improved dielectric temperature stability. When x  = 0.4, optimized dielectric ceramics are obtained with ε 25°C  = 1820, tanδ = 0.009, resistivity of 1.0 × 10 11  Ω·cm, which meets the EIA X7R standard (−55 °C - 125 °C, TCC ≤ ± 15 %).