Relaxor ferroelectric ceramics have very high dielectric constant (εr) but relatively low electrical breakdown strength (Eb), while glass–ceramics exhibit higher Eb due to the more uniformly dispersed amorphous phases and submicrocrystals/nanocrystals inside. How to effectively combine the advantages of both relaxor ferroelectric ceramics and glass–ceramics is of great significance for the development of new dielectric materials with high energy storage performance. In this work, we firstly prepared BaO–SrO–Bi2O3–Na2O–TiO2–Al2O3–SiO2 (abbreviated as GS) glass powders, and then fabricated (Ba0.3Sr0.7)0.5(Bi0.5Na0.5)0.5TiO3 + x wt% GS ceramic composites (abbreviated as BS0.5BNT–xGS, x = 0, 2, 6, 10, 14, 16, and 18). Submicrocrystals/nanocrystals with a similar composition to BS0.5BNT were crystalized from the glass, ensuring the formation of uniform core–shell structure in BS0.5BNT–xGS relaxor ferroelectric ceramic/glass–ceramic composites. When the addition amount of GS was 14 wt%, the composite possessed both high εr (> 3200 at 1 kHz) and high Eb (≈ 170 kV/cm) at room temperature, and their recoverable energy storage density and efficiency were Wrec = 2.1 J/cm3 and η = 65.2%, respectively. The BS0.5BNT–14GS composite also had several attractive properties such as good temperature, frequency, cycle stability, and fast charge–discharge speed. This work provides insights into the relaxor ceramic/glass–ceramic composites for pulsed power capacitors and sheds light on the utilization of the hybrid systems.
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Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (Wrec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which Ba0.105Na0.325Sr0.245-1.5x▯0.5xBi0.325+xTiO3 (BNS0.245-1.5x▯0.5xB0.325+xT, x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The BNS0.245-1.5x▯0.5xB0.325+xT ceramics are prepared by using pressureless solid-state sintering and achieve large Wrec (1.8 J/cm3) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm3 is super high as compared to all other Wrec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40-350 ℃ is also obtained in BNS0.245-1.5x▯0.5xB0.325+xT (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (Pr) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the BNS0.245-1.5x▯0.5xB0.325+xT (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi0.5Na0.5TiO3 (BNT)-based ceramics with high Wrec and high-temperature stability.
Dielectric ceramic capacitors, with the advantages of high power density, fast charge- discharge capability, excellent fatigue endurance, and good high temperature stability, have been acknowledged to be promising candidates for solid-state pulse power systems. This review investigates the energy storage performances of linear dielectric, relaxor ferroelectric, and antiferroelectric from the viewpoint of chemical modification, macro/microstructural design, and electrical property optimization. Research progress of ceramic bulks and films for Pb-based and/or Pb-free systems is summarized. Finally, we propose the perspectives on the development of energy storage ceramics for pulse power capacitors in the future.
(Ba0.3Sr0.7)x(Bi0.5Na0.5)1-xTiO3 (BSxBNT, x = 0.3–0.8) ceramics were prepared to investigate their structure, dielectric and ferroelectric properties. BSxBNT ceramics possess pure perovskite structure accompanied from a tetragonal symmetry to pseudo-cubic one with the increase of x value, being confirmed by X-ray diffraction (XRD) and Raman results. The Tm corresponding to a temperature in the vicinity of maximum dielectric constant gradually decreases from 110 ℃ (x = 0.3) to –45 ℃ (x = 0.8), across Tm = 36 ℃ (x = 0.5) with a maximum dielectric constant (ɛr = 5920 @1 kHz) around room temperature. The saturated polarization Ps gradually while the remnant polarization Pr sharply decreases with the increase of x value, making the P–E hysteresis loop of BSxBNT ceramics goes slim. A maximum difference between Ps and Pr (Ps–Pr) is obtained for BSxBNT ceramics with x = 0.5, at which a high recoverable energy density (Wrec = 1.04 J/cm3) is achieved under an applied electric field of 100 kV/cm with an efficiency of η = 77%. Meanwhile, the varied temperature P–E loops, fatigue measurements, and electric breakdown characteristics for the sample with x = 0.5 indicate that it is promising for pulsed power energy storage capacitor candidate materials.