Linear-like NaNbO3-based Lead-free Relaxor Antiferroelectric Ceramics with Excellent Energy-storage and Charge-discharge Properties
Antiferroelectric(AFE)materials exhibit great potential in the application of high-performance dielectric energy storage capacitors due to their electric field-induced AFE-ferroelectric(FE)phase transition.However,the large hysteresis of field-induced phase transition makes it difficult to simultaneously achieve high energy-storage density(Wrec)and efficiency(η)for AFEs.This work improved the energy-storage performance of NaNbO3-based lead-free AFE ceramics by introducing the third group Bi(Mg0.5Ti0.5)O3 into 0.76NaNbO3-0.24(Bi0.5Na0.5)TiO3 to regulate its relaxation characteristics.Novel lead-free AFE ceramics,(0.76-x)NaNbO3-0.24(Bi0.5Na0.5)TiO3-xBi(Mg0.5Ti0.5)O3,were prepared by a traditional solid-state reaction method.Their phase structure and microstructure as well as dielectric,energy-storage,and charge-discharge characteristics were studied.The results indicated that introduction of Bi(Mg0.5Ti0.5)O3 obviously enhanced the dielectric relaxor behavior of the matrix without changing its AFE R-phase structure,which led to the significantly reduced polarization hysteresis.Especially,a linear-like polarization-field hysteresis loop with extremely-low hysteresis was obtained in the composition of x=0.050.At the same time,microstructure of the ceramic was effectively optimized,its dielectric constant decreased,and its breakdown strength had significant enhanced.As a result,a high Wrec=3.5 J/cm3 and a high η=93%were simultaneously achieved under a moderate electric field of 30 kV/mm in the x=0.050 ceramic.Moreover,the x=0.050 ceramic also exhibited excellent charge-discharge characteristics with a high-power density PD=131(1±1%)MW/cm3,a high discharge energy density WD=1.66(1±6%)J/cm3 and a fast discharge rate t0.9<290 ns at 20 kV/mm.The charge-discharge properties maintained good stability within a wide temperature range of 25-125℃.These results indicate that 0.71NaNbO3-0.24(Bi0.5Na0.5)TiO3-0.050Bi(Mg0.5Ti0.5)O3 ceramics can be expected to be applied in high-power energy-storage capacitors.
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