Flash sintering BaTiO3-0.01MgO-0.01Nb2O5-xBi2O3 ceramics with superior dielectric temperature stability via defect engineering

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In this paper, Bi2O3 doped BaTiO3-0.01MgO-0.01Nb2O5 ceramics are designed to increase dielectric constant, reduce dielectric loss and improve temperature dielectric stability through inducing defects, and are prepared by flash sintering method to inhibit the volatilization of Bi element and ensure the element ratio. The microstructure, polarization mechanisms, dielectric properties and conduction mechanism of the ceramics are studied. The doping of Bi2O3 can enhance the relaxation behavior and dielectric properties. The defects evolution in BaTiO3-0.01MgO-0.01Nb2O-0.01Bi2O3 ceramics are studied. The results show that the BaTiO3 ceramics doped with different amounts of Bi2O3 can form defect dipoles {[BiBa∙‐MgTi″‐BiBa∙]×, [NbTi∙‐VBa″‐NbTi∙]×, [MgTi″‐VO∙∙]×} and oxygen vacancy, which enhance the short-range transition within the grain and inhibit the movement of free electrons at the grain boundary. The ceramics have excellent room temperature properties, high dielectric constant (εr = 2894) and low dielectric loss (tanδ < 0.03). The ceramics have superior temperature stability and satisfying the EIA X8R (Δεr/ε25 ≤ ±15 %, over the temperature range from −55 °C to 150 °C). It is found that flash sintering can effectively guarantee the stoichiometric concentration of bismuth element and obtain good properties of ceramics. This study demonstrates the potential of Bi2O3 doped BaTiO3-based ceramics synthetized by flash sintering as high-performance electronic device materials.