Phase-Transition Induced Optimization of Energy Storage and Temperature Stability of NaNbO₃ Doped BNBST Ceramics

Abstract

The 0.5Bi0.5Na0.5TiO3-0.5Ba0.3Sr0.7TiO3 (BNBST) ceramic is a relatively good relaxation component with tripartite phase and tetragonal phase coexisting at room temperature. Tripartite R3c is a polar phase, which can transform to long range ordered ferroelectric structures under the action of an applied electric field, exhibiting large remnant polarization (Pr), which limits its application in energy storage. In this work, we have designed and fabricated the NaNbO3 (NN) modified Bi0.5Na0.5TiO3-Ba0.3Sr0.7TiO3 (1-x)BNBST-xNN relaxor ferroelectrics. By increasing the NN amount, the phase composition is regulated to induce the transformation of the polar phase R3c to the weakly polar phase P4bm, leading to a smaller Pr. The ferroelectric test results show that the ceramic sample with x = 0.1 achieves a high effective energy storage density (Wrec = 2.58 J/cm3) and energy storage efficiency (ƞ = 91 %) at 140 kV/cm.