Novel (1-x)NaNbO3-xBi2/3HfO3 based, lead-free compositions with stable antiferroelectric phase and high energy density and switching field

Pulse power devices urgently need lead-free compositions with stable antiferroelectric phase and transition field. Following the guidance of the DFT (Density Functional Theory) calculation, a novel antiferroelectric composition (1-x)NaNbO3-xBi2/3HfO3(0 < x < 0.08), was designed and prepared, exhibiting well-documented double AFE loops both in macro and nanoscale. Furthermore, Bi2/3HfO3 modified compositions also exhibit a high stored energy density of 4.26 J/cm3, forward switching field of 225 kV/cm, large discharge current of 36 A, within 25 ns discharge time and high power density of 32 MW/cm3, which is superior to other NaNbO3-based compositions reported in antiferroelectric range. Structural analysis shows that the high temperature phases of P and R can be rapidly shifted to room temperature by adding Bi2/3HfO3. Combining results from the PFM and TEM, the modified compositions had a faster domain switching speed to the electric field. In addition, theoretical calculations demonstrated that modified compositions have a predictable increasing energy difference -7.48 meV/f.u. between AFE(antiferroelectric) and FE(ferroelectric) phase.