Ultrahigh Energy Storage Capacitors Based on Freestanding Single-Crystalline Antiferroelectric Membrane/PVDF Composites

Inorganic/organic dielectric composites are very attractive for high energy density electrostatic capacitors. Usually, linear dielectric and ferroelectric materials are chosen as inorganic fillers to improve energy storage performance. Antiferroelectric (AFE) materials, especially single-crystalline AFE oxides, have relatively high efficiency and higher density than linear dielectrics or ferroelectrics. However, adding single-crystalline AFE oxides into polymers to construct composite with improved energy storage performance remains elusive. In this study, high-quality freestanding single-crystalline PbZrO₃ membranes are obtained by a water-soluble sacrificial layer method. They exhibit classic AFE behavior and then 2D–2D type PbZrO₃/PVDF composites with the different film thicknesses of PbZrO₃ (0.1-0.4 µm) is constructed. Their dielectric properties and polarization response improve significantly as compared to pure PVDF and are optimized in the PbZrO₃(0.3 µm)/PVDF composite. Consequently, a record-high energy density of 43.3 J cm⁻³ is achieved at a large breakdown strength of 750 MV m⁻¹. Phase-field simulation indicates that inserting PbZrO₃ membranes effectively reduces the breakdown path. Single-crystalline AFE oxide membranes will be useful fillers for composite-based high-power capacitors.     

Optimal design of optical performance of reflective ferroelectric‐ and anti‐ferroelectric liquid‐crystal displays

Abstract— In an in‐plane optical geometry, such that the average optic axis lies on the plane parallel to both substrates, the optical properties of a reflective ferroelectric liquid‐crystal (FLC) or antiferroelectric liquid‐crystal (AFLC) cell were studied within the framework of the 2 × 2 Jones matrix formalism. To obtain good achromaticity and high brightness, the cell parameters such as the molecular rotation angle and the effective phase retardation of the AFLC layer were optimized. The device performances of the AFLC cell were experimentally demonstrated in this geometry.     

弓形液晶分子研究进展

具有弯曲刚性核的弓形非手性液晶分子（香蕉形分子）能形成众多新型液晶相，尤为引人注目的是它们的极性排列能导致超分子手性行为，所呈现的铁电性。反铁电性及铁磁性在光电领域有广泛的应用前景。介绍了弓形分子的结构特点、合成、性质及应用前景。     

前驱体溶剂对铅基反铁电厚膜介电性能的影响

采用sol-gel工艺制备了Pb0.97La0.02(Zr0.95Ti0.05)O3反铁电厚膜材料,研究了不同前驱体溶剂(乙酸和乙二醇乙醚)对反铁电厚膜介电性能的影响。结果表明:由乙二醇乙醚作为前驱体溶剂制备的反铁电厚膜材料,在室温下反铁电态稳定,其AFE-FE相的相变电场强度为184.05×103V/cm,FE-AFE相的相变电场强度为68.24×103V/cm,饱和极化强度为88.8×10-6C/cm2。     

High pyroelectric response in Pb0.99Nb0.02[(Zr0.57Sn0.43)1−xTix]0.98O3 ceramics

Both high pyroelectric coefficient and figure of merits of ferroelectric materials are desirable for infrared detection. In this work, we prepared Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_1−xTi_x]_0.98O₃ (0.060 ≤ x ≤ 0.080) ceramics, and the microstructure and electric properties were studied systematically. It is observed that the composition x = 0.07 shows enhanced pyroelectric properties around ambient temperature due to the ferroelectric–antiferroelectric phase transition, with the pyroelectric coefficient p = 6.83 × 10⁻⁴ C m⁻² K⁻¹ and the figures of merit F_i = 5.04 × 10⁻¹⁰ m V⁻¹, F_v = 7.61 × 10⁻² m² C⁻¹, and F_d = 3.46 × 10⁻⁵ Pa^−1/2 at room temperature and the highest pyroelectric coefficient of 695.5 × 10⁻⁴ C m⁻² K⁻¹ and F_i = 1410.46 × 10⁻¹⁰ m V⁻¹, F_v = 1587.39 × 10⁻² m² C⁻¹, and F_d = 1182.94 × 10⁻⁵ Pa^−1/2 at 36.7°C. These values are superior to other pyroelectric materials. These results indicate that this system is a promising pyroelectric material for the applications of infrared detectors.     

NaNbO3-based short-range antiferroelectric ceramics with ultrahigh energy storage performance

Lead-free NaNbO₃ (NN) antiferroelectric ceramics provide superior energy storage performance and good temperature/frequency stability, which are solid candidates for dielectric capacitors in high power/pulse electronic power systems. However, their conversion of the antiferroelectric P phase to the ferroelectric Q phase at room temperature is always accompanied with large remnant polarization (P_r), which significantly reduces their effective energy storage density and efficiency. In this study, to optimize the energy storage properties, short-range antiferroelectric (0.95-x)NaNbO₃-xBi(Mg_2/3Nb_1/3)O₃-0.05CaZrO₃ (xBMN) ceramics were designed to stabilize the antiferroelectric phase, in which the local random fields were simultaneously constructed. The results showed that the antiferroelectric orthorhombic P phase was transformed into the R phase, and the local short-range random fields were generated, which effectively inhibited the hysteresis loss and P_r. Of great interest is that the 0.12BMN ceramics displayed a large recoverable energy storage density (W_rec) of 5.9 J/cm³ and high efficiency (η) of 85% at the breakdown strength (E_b) of 640 kV/cm. The material also showed good frequency stability in the frequency range of 2–300 Hz, excellent temperature stability in the temperature range of 20–110 ℃, and a very short discharge time (t_0.9∼4.92 μs). These results indicate that xBMN ceramics have great potential for advanced energy storage capacitor applications.     

(Na0.8K0.2)0.5Bi0.5TiO3陶瓷的介电压电性能

研究了(Na0.8K0.2)0.5Bi0.5TiO3陶瓷的介电和压电性能,发现陶瓷从室温到500℃温度范围的介电谱中存在两个介电峰,电滞回线显示第一个介电峰由铁电-反铁电相变引起的,温度继续升高,反铁电相由宏畴变为微畴,微畴向顺电相转变导致了第二个介电峰,该峰对应的相变为弥散型相变.室温下陶瓷具有较高的剩余极化强度Pr=29.4μC/cm2和相对低的矫顽电场Ec=2.8kV/mm,极化后的陶瓷显示出较高的压电常数d33=120pC/N和机电耦合系数Kp=28.5%,以及高的频率常数Nφ=2916Hz.m,120℃具有最小的谐振频率温度系数.     

Structure variation and energy storage properties of acceptor-modified PBLZST antiferroelectric ceramics

Energy storage capacitors with high recoverable energy density and efficiency are greatly desired in pulse power system. In this study, the energy density and efficiency were enhanced in Mn-modified (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃ antiferroelectric ceramics via a conventional solid-state reaction process. The improvement was attributed to the change in the antiferroelectric-to-ferroelectric phase transition electric field (E_F) and the ferroelectric-to-antiferroelectric phase transition electric field (E_A) with a small Mn addition. Mn ions as acceptors, which gave rise to the structure variation, significantly influenced the microstructures, dielectric properties and energy storage performance of the antiferroelectric ceramics. A maximum recoverable energy density of 2.64 J/cm³ with an efficiency of 73% was achieved when x = 0.005, which was 40% higher than that (1.84 J/cm³, 68%) of the pure ceramic counterparts. The results demonstrate that the acceptor modification is an effective way to improve the energy storage density and efficiency of antiferroelectric ceramics by inducing a structure variation and the (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃-xMn₂O₃ antiferroelectric ceramics are a promising energy storage material with high-power density.     

反铁电材料的应用研究

本文介绍了反铁电体材料的特性及其在储能电容器方面的应用。