Reducing Applied Field in Nbt-Based High Energy-Storage Ceramics Via B-Site Entropy Regulation

Abstract

Recently, ceramics have raised much interest for high-power and high-energy capacitors applications. The Wrec (recoverable energy density) generally increases with applied E (electric field). Thus, the high-field properties must be excellent. Due to enhanced degradation, lower fields would be, nevertheless, preferable. We proposed a novel strategy to improve simultaneously the tolerance factor and configurational entropy based on the composition of (1-x)NBT-xBMZNT. This leads to a high Wrec (1.32 J/cm3) and a high efficiency η (99%) under a low E of 100 kV/cm, which is superior to other ceramic components. The discharge test furthermore illustrates a high Wd (>0.8 J/cm3) over the temperature range from 20 to 160 oC caused by the high permittivity ~2700±15% from 50 oC to 370 oC. XRD and Raman results present that BMZNT can fully diffuse into the NBT lattice when x<0.18. Furthermore, BMZNT addition also increases the lattice symmetry and volume. Modulus M″ and Piezo-Force-Microscopy (PFM) results demonstrate that sheetlike domains gradually become fragmented to PNRs (polar nanoregions), leading to their rapid response to the applied E. Our work will provide a entropy regulation strategy to reduce the applied field without compromising the energy-storage performance.

Keywords: Na0.5Bi0.5TiO3, entropy regulation, applied field