High-Performance BNT-Based Ferroelectric Ceramics With Simultaneously Enhanced Polarization and Breakdown Strength
high energy storage,high polarization,high breakdown strength,temperature stability
Mineral Materials and Advanced Energy Materials > 8. New Energy Materials
Abstract Accepted
子明 蔡 / 中国矿业大学
培忠 冯 / 中国矿业大学
航 杨 / 中国矿业大学
ABSTRACT:BNT(Bi0.5Na0.5TiO3)-based ferroelectric ceramics have drawn much attention in energy-storage field due to the high polarization and good temperature stability. However, the reduction of Ti4+ caused by the volatilization of Bi and Na elements during high-temperature sintering is a huge problem. Multivalence element (Mn) is adopted in this work to prevent the reduction of Ti4+, and thus enhance the polarization and breakdown strength simultaneously. Various content of MnO2 doped (0.95Bi0.5Na0.5TiO3-0.05SrZrO3)-0.2NaNbO3 (BNTSZNN) ceramics were prepared by the Ramp-to-spike sintering method. The existence of Ti3+, confirmed by the X-ray photoelectron spectroscopy (XPS), proves the reduction of Ti4+. As the content of MnO2 increases, the content of Ti3+ is effectively decreased, reducing the degradation of ferroelectricity and leakage conductance. As a result, an ultra-high discharge energy density (Wrec) of 7.05 J/cm3 is achieved in the BNTSZNN-0.15MnO2 ceramic at 387 kV/cm. Importantly, the BNTSZNN-0.15MnO2 ceramic system behaves quite excellent temperature stability both in energy-storage and capacitance field. The variation in the discharge energy density (Wrec) is less than ±4% in the temperature range from 30 °C to 160 °C under the applied field of 120 kV/cm. Additionally, the variation in the capacitance (or dielectric permittivity) of the BNTSZNN-0.15 MnO2 ceramic is less than ±15% over the temperature range from -55 °C to 450 °C, with a high room temperature dielectric permittivity of 1507. All the above characteristics indicate the potential of BNTSZNN-0.15MnO2 as high-temperature and high-voltage ceramic dielectrics.
KEYWORDS: anti-reduction, energy storage, high polarization, high breakdown strength, temperature stability