Superior Thermal Stability of High Energy Density and Power Density in Domain-Engineered BiNaTiO-NaTaO Relaxor Ferroelectrics.

Thermal-stable dielectric capacitors with high energy density and power density have attracted increasing attention in recent years. In this work, (1 - )BiNaTiO-NaTaO [(1 - )BNT-NT, = 0-0.30] lead-free relaxor ferroelectric ceramics are developed for capacitor applications. The = 0.20 ceramic exhibits superior thermal stability of discharged energy density () with a variation of less than 10% in an ultrawide temperature range of -50 to 300 °C, showing a significant advantage compared with the previously reported ceramic systems. The reaches 4.21 J/cm under 38 kV/mm at room temperature. Besides, a record high of power density ( ≈ 89.5 MW/cm) in BNT-based ceramics is also achieved in = 0.20 ceramic with an excellent temperature insensitivity within 25-160 °C. The = 0.20 ceramic is indicated to be an ergodic relaxor ferroelectric with coexisted 3 nanodomains and 4 polar nanoregions at room temperature, greatly inducing large maximum polarization, maintaining low remnant polarization, and thus achieving high and . Furthermore, the diffuse phase transition from 3 to 4 phase on heating is considered to be responsible for the superior thermal stability of the high and . These results imply the large potential of the 0.80BNT-0.20NT ceramic in temperature-stable dielectric capacitor applications.