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Strength prediction under the action of pores is crucial for the safety of ceramics. Here, a quantitative prediction model of pore-strength response under mode-I loading was developed based on the new mapping relationship between stress intensity factor and tip radius. The new model was proved to have great application after comparison and analysis of the pore-strength test data of three typical ceramics as well as the pertinent data as-reported in the literature. Results indicated that when the tip radius of pore (ρ) exceeds the critical value (ρ c = K Ic 2/(π σ 0 2)), the stress intensity factor increases as a power function with increasing ρ , at which point the strength decay is significantly weakened, and when the ρ is lower than the ρ c , the pore can be equated to a crack problem. This work can not only forecast and assess the failure strength of ceramics containing pores, but also provide guidance for the design of extremely dependable ceramics. [ABSTRACT FROM AUTHOR]

Na 0.5 Bi 0.5 TiO 3 -based relaxor ferroelectric ceramics have attracted widespread attention due to their potential applications in energy storage capacitors for pulse power system. We herein propose a synergistic strategy of introduction of 6s2 lone pair electrons, breaking the long-range ferroelectric order, and band structure engineering for high performance energy storage by introducing Bi(Mg 0.5 Sn 0.5)O 3 (BMS) with weak ferroelectric active cations into 0.7Na 0.5 Bi 0.5 TiO 3 -0.3SrTiO 3 (BNT-ST) to form BNT-ST-BMS ceramics. The doped ceramics display the excellent dielectric stability versus temperature and frequency. The suitable BMS doping can increase the band gap of the BNT-ST ceramic and effectively avoids early dielectric breakdown and polarization saturation. The BNT-ST-BMS ceramic in the composition of x = 0.08 exhibits an outstanding recoverable energy storage density (W rec) of 5.99 J/cm3, together with a good efficiency (ƞ) of 76% as well as an excellent dielectric stability versus temperature (Δε r /ε r(150°C) ≤ ±15%) and frequency. The findings in this work demonstrate that the BNT-ST-BMS ceramics have exceptional potential as candidate materials for pulse power and high voltage capacitors applications, and provide a path for the development of the other lead-free energy storage materials. [ABSTRACT FROM AUTHOR]

Na 0.5 Bi 0.5 TiO 3 -based relaxor ferroelectric ceramics have attracted widespread attention due to their potential applications in energy storage capacitors for pulse power system. We herein propose a synergistic strategy of introduction of 6s2 lone pair electrons, breaking the long-range ferroelectric order, and band structure engineering for high performance energy storage by introducing Bi(Mg 0.5 Sn 0.5)O 3 (BMS) with weak ferroelectric active cations into 0.7Na 0.5 Bi 0.5 TiO 3 -0.3SrTiO 3 (BNT-ST) to form BNT-ST-BMS ceramics. The doped ceramics display the excellent dielectric stability versus temperature and frequency. The suitable BMS doping can increase the band gap of the BNT-ST ceramic and effectively avoids early dielectric breakdown and polarization saturation. The BNT-ST-BMS ceramic in the composition of x = 0.08 exhibits an outstanding recoverable energy storage density (W rec) of 5.99 J/cm3, together with a good efficiency (ƞ) of 76% as well as an excellent dielectric stability versus temperature (Δε r /ε r(150°C) ≤ ±15%) and frequency. The findings in this work demonstrate that the BNT-ST-BMS ceramics have exceptional potential as candidate materials for pulse power and high voltage capacitors applications, and provide a path for the development of the other lead-free energy storage materials. [ABSTRACT FROM AUTHOR]