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•The effect of ST and BMH doping in BNT on energy storage properties were studied.•By modifying composition, good energy storage properties are obtained in BNST-BMH.•Ultrahigh Wrec of ...5.59 J/cm3and η of 85.3% are realized in BNST-BMH ceramic.•BNST-BMH ceramic exhibits excellent thermal stability from 20 °C to 140 °C.•A superior fatigue resistance over 105 cycles was achieved in BNST-BMH ceramic.
Dielectric ceramic capacitors with high energy density are one of the great bright energy storage devices. Here, the Bi0.5Na0.5TiO3, 0.75Bi0.5Na0.5TiO3-0.25SrTiO3, 0.65Bi0.5Na0.5TiO3-0.35SrTiO3 and 0.88(0.65Bi0.5Na0.5TiO3-0.35SrTiO3)-0.12Bi(Mg0.5Hf0.5)O3, (abbreviated as BNT, BNT-25ST, BNT-35ST and BNST-BMH, respectively) ceramics were produced by solid state sintering method. The influence of solid solution of SrTiO3 and Bi(Mg0.5Hf0.5)O3 doping in Bi0.5Na0.5TiO3 on crystal structure, microstructure, electrical and energy storage performance were evaluated systematically. By optimizing ceramics composition, high breakdown field and slim hysteresis loops were simultaneously realized due to enhanced band gap, refined grain size and nano-domains formed, which can be verified by the transmission electron microscope (TEM), piezoelectric force microscope (PFM) and ultraviolet–visible spectrum. Therefore, an ultrahigh recoverable energy density of 5.59 J/cm3 with brilliant efficiency of 85.3% is realized in BNST-BMH ceramic. Besides, the BNST-BMH also exhibits prominent temperature stability at 20–140 °C, superior fatigue resistance beyond 105 cycles and outstanding frequency stability at 1–200 Hz. Our work offers a novel way for designing dielectric capacitors and also proves that BNST-BMH is indeed a great hopeful dielectric energy storage material in pulse power electronics.
•A high Wr of 4.97 J/cm3 and an η of 84.4% are obtained in BNT-based ceramics.•The Wr of 2.73 J/cm3 with η of 80.6% are obtained at 140 ℃.•A superior temperature performance compared with other ...typical dielectric materials.•A strategy of precisely adjusting the relaxation and ferroelectricity states.
Dielectric energy storage materials have attracted much attention because of their wide applications in the electronics industry. However, low energy storage density and poor thermostability limit their application. In this work, a strategy was proposed to prepare lead-free relaxor ferroelectric ceramics with ultra-high energy storage properties and superior temperature stability by precisely adjusting the relaxation and ferroelectricity states and increasing the electric field intensity. An ultra-high recoverable energy storage density (Wr) of 4.97 J/cm3 and an efficiency (η) of 84.4% are simultaneously obtained for the 0.95(0.9Bi0.5Na0.5TiO3-0.1Ba0.85Ca0.15Zr0.1Ti0.9O3)-0.05BaSnO3 ceramic. Moreover, a high Wr of 2.73 J/cm3 with brilliant η of 80.6% are obtained in the ceramic at 140 ℃ and there is almost no thermal degradation of energy storage properties from 25 ℃ to 140 ℃. The Wr and η have decreased by 2.2% and 1.9% after 105 cycles under 200 kV/cm, respectively, which demonstrates the good cycle stability of the sample. A discharge power density of up to 99.0 MW/cm3 is obtained in the 0.95(0.9Bi0.5Na0.5TiO3-0.1Ba0.85Ca0.15Zr0.1Ti0.9O3)-0.05BaSnO3 ceramic and the good charge and discharge performance of this sample is important for practical applications.
The dielectric and piezoelectric properties of La-modified Pb(Mg1/3Nb2/3)O3-xPbTiO3 crossover ceramics were systematically studied. In this crossover region, there is a ferroelectric-relaxor boundary ...separating the ferroelectric and relaxor states, which is determined by the spontaneous transition from relaxor to ferroelectric state with decreasing temperature. At the ferroelectric-relaxor boundary, the maximum permittivity increases from 18,200 to 23,500, and piezoelectric coefficient (d33) increases from 300 pC/N to 450 pC/N accompanied by the electrostrain improved from 0.09% to 0.12%, as compared with adjacent ferroelectric specimen. These enhancements may originate from the low energy barrier for polarization rotation induced by the existence of spontaneous transition and the coexistence of macrodomain and polar nanodomain configuration. This work indicates that the ferroelectric-relaxor boundary in crossover region may become an effective approach to enhance the dielectric and piezoelectric properties of ferroelectric materials.
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•Local phase coexistence enhances the ESPs of the (1−x)BNT-xSLZT ceramics.•The Wrec of 5.09 J/cm3 and η of 88% are achieved in 0.67BNT-0.33SLZT ceramic.•The ceramic displays good thermal stability ...from 0 °C to 200 °C.•The coexistence of P4bm and Pm-3 m phases increases the Eb of the ceramic.
Dielectric capacitors with excellent energy storage performance are highly desirable for electronic industry. Although many excellent studies have been carried out on energy-storage dielectric materials, the explanation of their macroscopic electrical properties from the microscopic point of view remains scarce. In this work, (1-x)Bi0.5Na0.5TiO3-xSr0.7La0.2Zr0.15Ti0.85O3 ((1-x)BNT-xSLZT) relaxor ceramics are designed and fabricated. The recoverable energy density of 5.09 J/cm3 and efficiency of 88% are achieved in 0.67BNT-0.33SLZT ceramic. The ceramic also displays an excellent thermal stability in a wide temperature range (0–200 °C). The good performance of the ceramics is attributed to their heterogeneous structure which contains two different local phases after composition modification. Micro-structure is then validated by the Rietveld refinement and transmission electron microscopy analysis. Moreover, the decrease in domain size and enhancement in domain reversibility are also observed in the sample. The delayed polarization saturation and increased electric field strength significantly enhance the energy storage properties of the ceramics. This work indicates that constructing local phase coexistence is an effective method for obtaining high-performance energy storage ceramics, and may provide a guideline for designing and preparation of dielectric energy storage ceramics with superior properties.
Dielectric energy-storage capacitors are of great importance for modern electronic technology and pulse power systems. However, the energy storage density (Wrec) of dielectric capacitors is much ...lower than lithium batteries or supercapacitors, limiting the development of dielectric materials in cutting-edge energy storage systems. This study presents a single-phase BaTiO3-based high-entropy (BT-H) ceramic, which is synthesized using a conventional solid-state reaction method. It is found that the BT-H ceramic exhibits a remarkable energy storage performance, with a Wrec of 5.18J/cm3 and an ultrahigh η of 93.7% at 640kV/cm electric field. Moreover, it also features wide temperature stability and excellent frequency stability. It is proposed that the introduction of high entropy enhances the random electric field and stress field, leading to lattice distortion and reduction of nanometer domain size, which in turn reduces remnant polarization and increases electric breakdown strength. This research provides a novel approach to improve the energy storage performance of ceramics through the high-entropy strategy.
•Two BT-based high-entropy oxide ceramics were prepared and studied. An ultrahigh Wrec of 5.18J/cm3 and an ultrahigh η of 93.7% at a 640kV/cm electric field were achieved in the BT-H (Mg) ceramics.•The doping of ions of various ionic radii and valence states into BaTiO3 disrupts the traditional long-range order of ferroelectrics, resulting in slim polarization-electric field (P-E) loops and enhanced energy storage efficiency.•The BT-H ceramics exhibit remarkable energy storage performance stability when the temperature is between 30 and 150 °C, the frequency is from 5 to 2000 Hz, and the number of cycles is from 1 to 105 times.
•Through modifying Sn4+ content, the breakdown strength is increased by 112.3%.•The recoverable energy density enhanced by 276.2% via incorporation of Sn4+.•The doping of Sn4+ inhibits the migration ...of grain boundary and refines grains.•The delayed polarization saturation result from Sn4+ with d10 substitutes Ti4+ with d0.
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High-performance dielectric ceramic capacitors is a promising candidate in energy storage devices. In this work, the energy storage performance of Ba0.94Ca0.06Ti1−xSnxO3 (x = 0.04, 0.08, 0.12, 0.16) ceramics was systematically studied. Through modifying Sn4+ doping content, the breakdown strength of the ceramics is enhanced by 112.3% from 133.4 kV/cm (Ba0.94Ca0.06Ti0.96Sn0.04O3) to 283.2 kV/cm (Ba0.94Ca0.06Ti0.84Sn0.16O3). Accordingly, the recoverable energy density is greatly increased by 276.2%, that is, from 0.42 J/cm3 grow to 1.58 J/cm3. The enhanced energy storage properties could be ascribed to the following aspects: (1) the doping of Sn4+ with a larger ionic radius inhibits the migration of grain boundaries and therefore refines grains, resulting in a higher activation energy and a larger Eb; (2) the long range polar order is broke and polar nano-regions are formed, giving rise to lower energy barrier and smaller Pr; (3) the weakened ferroelectricity and delayed polarization saturation lead to higher Wrec owing to the fact that Sn4+ with d10 electronic configurations substitutes Ti4+ with d0. Our work provides a novel approach for enhancing energy storage performance in dielectric ceramic capacitors.
CeO2-HfO2 solid solution thin films (Hf1-xCexO2) were deposited on Pt(111)/TiO2/SiO2/Si(100) substrates using the chemical solution deposition method. This study investigates the influence of CeO2 ...content and annealing temperature on the structure and ferroelectric properties of Hf1-xCexO2 films. Ferroelectric behavior is demonstrated in polycrystalline Hf0.80Ce0.20O2 films with thicknesses ranging from 163 to 524 nm. And the structure of the films is analyzed using glancing incidence X-ray diffraction. The comprehensive results indicate that Hf0.80Ce0.20O2 films annealed at 850 °C exhibit excellent ferroelectricity. Square hysteresis loops associated with the ferroelectric orthorhombic phase are observed, even in the 524-nm-thick film. The remnant polarization (Pr) and coercive field (Ec) range from 16 to 18 μC/cm2 and 1100–1250 kV/cm, respectively, under a maximum applied electric field of 2 MV/cm for all Hf0.80Ce0.20O2 films. Furthermore, the film presents thickness-insensitive characteristic. The current work paves the new way to design high-performance thick HfO2-based ferroelectric films.
•Ca2+ and Sr2+ can increase the stability of antiferroelectric phase while Ba2+ decreases it.•An enhanced negative ECE of ΔT around − 10.6 K was obtained in the Pb0.9Sr0.1ZrO3 thin film at room ...temperature.•The modification of antiferroelectric-ferroelectric phase transition is an effective strategy to enhance the negative electrocaloric effect in antiferroelectric thin films.
In the Pb0.9Sr0.1ZrO3 thin film, an enhanced negative electrocaloric effect (ECE) has been observed based on the Maxwell relation, with ΔT of around − 10.6 K under 450 kV/cm at room temperature, as compared with the pristine PbZrO3 thin film (with ΔT of around −7.3 K under 300 kV/cm at 361 K), as shown in the figure. Our work demonstrates that modifying antiferroelectric-ferroelectric phase transition is an effective way to enhance the negative ECE in antiferroelectric thin films. Display omitted
Electrocaloric effect (ECE) in dielectric materials has attracted much attention due to its promising applications in solid-state cooling devices. In this work, alkaline-earth doped PbZrO3 antiferroelectric thin films (Pb0.9A0.1ZrO3 (A=Ca, Sr, and Ba)) were deposited by a sol-gel method and its antiferroelectric-ferroelectric phase competition as well as the negative ECE were studied. It is found that Ca2+ and Sr2+ expand the antiferroelectric phase region while Ba2+ reduces it, due to the different ion radii of these alkaline-earth elements. As a result, the Pb0.9Sr0.1ZrO3 thin film exhibits an enhanced negative ECE with ΔT of around − 10.6 K under 450 kV/cm whereas the Pb0.9Ba0.1ZrO3 thin film shows a decreased negative ECE with ΔT of around − 2.5 K under 200 kV/cm, as compared with the pristine PbZrO3 thin films (with ΔT of around −7.3 K under 300 kV/cm). This work provides an effective method to enhance the negative ECE of antiferroelectrics in electrical cooling applications by adjusting their antiferroelectric to ferroelectric phase transition.
Design and simulation study on the corn precision dibbler based on the ADAMS Zhao Jiantuo, Gansu Agricultural University, Lanzhou(China), College of Engineering; Zhao Wuyun, Gansu Agricultural University, Lanzhou(China), College of Engineering; Ren Yanhua, Lanzhou Vocational Technical College,Lanzhou(China0
Gansu nong ye da xue xue bao,
Oct. 2010, Letnik:
45, Številka:
5
Journal Article
针对目前玉米穴播器存在空穴率较高,穴粒数均匀度差等问题,设计了玉米精密穴播器,确定了穴播器主要技术参数,采用精密排种器和鸭嘴强制开启机构,确保播种质量.在ADAMS/View环境下用相对轨迹曲线生成实体的方法,进行了鸭嘴强制开启机构的凸轮设计,进行了仿真研究,测试了鸭嘴的摆角、角速度、角加速度.结果表明：鸭嘴开始播种时快速开启,保持到出土后再逐渐关闭,满足穴播器设计要求.著者文摘
A corn ...precision dibbler was designed aiming to solve the problems of high rate of empty seed and asymmetry of seeding,etc.The main technology parameters of dibbler were determined.The precision metering device and compulsive cam opening device were used to ensure the quality of seeding.The duck-beak compulsive opening device was simulated to measure the duck-beaks swing angle,angular velocity and angular acceleration,with the cam of duck-beak compulsive opening device designed based on the relative path curves in the ADAMS/view.The simulation results showed that the dibbler meets the requirement of design.著者文摘
