Dielectric and Energy Storage Properties of(1-x)NaNbO3-x(0.3Bi0.5Na0.5TiO3-0.7BiFeO3)Ceramics
Sodium niobate(NaNbO3)ceramic,as a representative of antiferroelectric materials,has been widely studied in the field of energy storage due to its environmental friendliness and non-toxicity.However,its application is greatly limited due to its square hysteresis loop,which leads to low recoverable energy storage density(Wrec).Introducing a second compo-nent into NaNbO3 to form a solid solution can enhance its energy storage properties.According to this train of thoughts,(1-x)NaNbO3-x(0.3Bi0.5Na0.5TiO3-0.7BiFeO3)[NN-x(BNT-BF)](x=0.05,0.1,0.15,0.2)ceramics were designed through substituting the A-and B-sites of NaNbO3 with Bi3+,Fe3+,and Ti4+simultaneously in this work.The NN-x(BNT-BF)ceram-ics were prepared by the conventional solid-state reaction method,and their phase compositions,microstructures,dielectric and energy storage properties were systematically investigated by X-ray diffraction(XRD),Raman spectrum,scanning elec-tron microscopy(SEM),dielectric property measurement and ferroelectric test.The results showed that with the increase of BNT-BF content,the phase composition of the NN-x(BNT-BF)ceramics gradually transformed from coexistence of orthogo-nal antiferroelectric P and R phases(x＜0.1)to single antiferroelectric R phase(x≥0.1),and the relaxation behavior was significantly enhanced.The densification of the NN-x(BNT-BF)ceramics was remarkably improved.With the increase of BNT-BF content,the average grain size of the NN-x(BNT-BF)ceramics was firstly declined and then increased.Moreover,replacing the A-and B-sites of NaNbO3 by Bi3+,Fe3+,and Ti4+simultaneously could disrupt its original long-range antiferro-electric ordered structure,thus optimizing energy storage performances of the ceramics.At a high breakdown field strength(Eb)of 410 kV/cm,the NN-0.2(BNT-BF)ceramic achieved Wree of 2.54 J/cm3,and energy storage efficiency(η)of 89.24％.In addition,the NN-0.2(BNT-BF)ceramic exhibited a high temperature stability in the temperature range of 20～120 ℃.Meanwhile,large power density(PD=49 MW/cm3),high current density(CD=406 A/cm2),and ultrafast discharge rate(t0.9=35 ns)made the NN-0.2(BNT-BF)ceramic have potential applications in pulse power systems.
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