Superior Thermal Stability of High Energy Density and Power Density in Domain-Engineered Bi0.5Na0.5TiO3–NaTaO3 Relaxor Ferroelectrics

Abstract

Thermal-stable dielectric capacitors with high energy density and power density have attracted increasing attention in recent years. In this work, (1 – x )Bi 0.5 Na 0.5 TiO 3 – x NaTaO 3 [(1 – x )BNT– x NT, x = 0–0.30] lead-free relaxor ferroelectric ceramics are developed for capacitor applications. The x = 0.20 ceramic exhibits superior thermal stability of discharged energy density ( W D ) 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 W D reaches 4.21 J/cm 3 under 38 kV/mm at room temperature. Besides, a record high of power density ( P D ≈ 89.5 MW/cm 3 ) in BNT-based ceramics is also achieved in x = 0.20 ceramic with an excellent temperature insensitivity within 25–160 °C. The x = 0.20 ceramic is indicated to be an ergodic relaxor ferroelectric with coexisted R 3 c nanodomains and P 4 bm polar nanoregions at room temperature, greatly inducing large maximum polarization, maintaining low remnant polarization, and thus achieving high W D and P D . Furthermore, the diffuse phase transition from R 3 c to P 4 bm phase on heating is considered to be responsible for the superior thermal stability of the high W D and P D . These results imply the large potential of the 0.80BNT–0.20NT ceramic in temperature-stable dielectric capacitor applications.