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排序方式: 共有6215条查询结果,搜索用时 31 毫秒
1.
Hao Chen Jie Xing Jingwen Xi Tao Pu Hong Liu Jianguo Zhu 《Journal of the American Ceramic Society》2021,104(12):6266-6276
The Ag-Pd internal electrode of multilayer piezoelectric ceramics needs to be sintered below 1000°C, and lead wires and components need to be welded with lead-free solder at 260°C. PNN–PMW–PZT–xSr piezoelectric ceramics with high Curie temperature (Tc > 260°C) were synthesized at a low sintering temperature (960°C) to meet the requirements of multilayer piezoelectric devices. The relationship between structures (phase, domain, and microstructures) and electrical properties (piezo/ferroelectric properties, and dielectric relaxation) in the Sr2+ substituted ceramics was investigated. Rietveld refinement and Raman spectra show that Sr2+ substitution can cause the phase change and increase the force constant of [BO6] octahedron. The piezoelectric response increases with increasing the content of the tetragonal phase (CTP) in the rhombohedral-tetragonal (R-T) coexisted ceramics. The ceramics with 0.6 mol% Sr2+ substitution have minimum activation energy for domain wall movement (Ea) of 0.0362 eV which favors the formation of nanometer-sized domains, and possess excellent electrical properties (d33 = 623 pC/N, d33* =783 pm/V, Tc =295°C). The higher the CTP, the lower the Ea. The lower Ea favors the rotation of polarization direction and extension, and is beneficial to the generation of the nanometer-size domains, resulting in high piezoelectric properties. 相似文献
2.
Yan He Kangren Kong Zhengxi Guo Weifeng Fang Zaiqiang Ma Haihua Pan Ruikang Tang Zhaoming Liu 《Advanced functional materials》2021,31(26):2101291
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. 相似文献
3.
Yueqiang LI Chao GAO Bin WU Yushuai WANG Haibo ZHENG Ming XUE Yuling WANG 《等离子体科学和技术》2021,23(2):25501-37
The turbulent boundary layer control on NACA 0012 airfoil with Mach number ranging from 0.3 to 0.5 by a spanwise array of dielectric barrier discharge(DBD)plasma actuators by hot-film sensor technology is investigated.Due to temperature change mainly caused through heat produced along with plasma will lead to measurement error of shear stress measured by hot-film sensor,the correction method that takes account of the change measured by another sensor is used and works well.In order to achieve the value of shear stress change,we combine computational fluid dynamics computation with experiment to calibrate the hot-film sensor.To test the stability of the hot-film sensor,seven repeated measurements of shear stress at Ma = 0.3 are conducted and show that confidence interval of hot-film sensor measurement is from-0.18 to 0.18 Pa and the root mean square is 0.11 Pa giving a relative error 0.5%over all Mach numbers in this experiment.The research on the turbulent boundary layer control with DBD plasma actuators demonstrates that the control makes shear stress increase by about 6%over the three Mach numbers,which is thought to be reliable through comparing it with the relative error 0.5%,and the value is hardly affected by burst frequency and excitation voltage. 相似文献
4.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献
5.
Dealloyed nanoporous gold (np-Au) has applications as oxygen reduction catalysis in Li-air batteries and fuel cells, or as actuators to convert electricity into mechanical energy. However, it faces the challenges of coarsening-induced structure instability, mechanical weakness due to low relative densities, and slow dealloying rates. Here, monolithic np-Au is dealloyed from a single-phase Au25Ni75 solid-solution at a one-order faster dealloying rate, ultra-low residual Ni content, and importantly, one-third more relative density than np-Au dealloyed from conventional Au25Ag75. The small atomic radius and low dealloying potential of the sacrificing element Ni are intrinsically beneficial to fast produce high relative density np-Au, as predicted by a general model for dealloying of binary alloys and validated by experiments. Stable, durable, and reversible actuation of np-Au takes place under cyclic potential triggering in alkaline and acidic electrolytes with negligible coarsening-induced strain-shift. The thermal and mechanical robustness of bulk np-Au is confirmed by two-order slower ligament coarsening rates during annealing at 300 °C and 45 MPa macroscopic yielding strength distinctive from the typical early onset of plastic yielding. This article opens a rich direction to achieve high relative density np-Au which is essential for porous network connectivity, mechanical strength, and nanostructure robustness for electrochemical functionality. 相似文献
6.
Julio E. Trevino Swati Mohan Alexandra E. Salinas Emilia Cueva Karen Lozano 《应用聚合物科学杂志》2021,138(28):50665
This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some. 相似文献
7.
The structure and properties of Mn-doped 0.67BiFeO3-0.33BaTiO3 ceramics are systematically investigated with respect to the effects of annealing prior to rapid cooling by quenching in air. Air-quenching induces a change in crystal structure from pseudo-cubic to rhombohedral, with higher quenching temperatures leading to an increased rhombohedral distortion. These structural changes are correlated with the appearance of more well-defined ferroelectric domain configurations. It is shown that the surface preparation procedures for XRD measurements can induce significant changes in the peak profiles, indicating differences in crystal structure between the surface and bulk regions. Frequency dispersion in the temperature-dependent relative permittivity for the as-sintered sample is significantly reduced after quenching, accompanied by enhancement of the Curie point and improved temperature-stability of piezoelectric properties. It is proposed that the formation of defect clusters by A-site cation diffusion during cooling is circumvented by quenching, leading to the observed modification of structural distortion and ferroelectric properties. 相似文献
8.
《Ceramics International》2021,47(21):30439-30447
Bismuth titanate (Bi4Ti3O12, BIT) exhibits a high Curie temperature and anisotropic electrical performance owing to its layered perovskite structure, and hence, it is an important ferroelectric material for high-temperature piezoelectric applications. It is crucial to understand the effects of the anisotropy in BIT-based ferroelectrics for developing novel high-temperature piezoelectric materials. In this study, a highly textured BIT ceramic was fabricated using the tape-casting technique from highly grain-oriented BIT platelets prepared by the molten salt method. The textured BIT ceramic showed a dense microstructure and high grain orientation along the (00l) plane with a texturing degree F00l = 0.86. It exhibited significant anisotropy in the electrical properties along the directions parallel and perpendicular to the axis of the tape-casting plane. Double ferroelectric hysteresis P–E loops and normal ferroelectric P–E loops were observed in the parallel and perpendicular samples, respectively. In addition to the layered crystal structure and domains, the anisotropy in the arrangement of the oxygen vacancy defects and their transport in the structure led to a significant anisotropy in the ferroelectric properties of the textured BIT ceramics. This work demonstrates the anisotropic arrangement of the oxygen vacancy defects and its effect on the electrical properties of high-temperature bismuth layer-structured ferroelectrics. 相似文献
9.
10.
Shaojie Zhang Wangshu Tong Jiang Wang Wenjiang Wang Zhihao Wang Yihe Zhang 《应用聚合物科学杂志》2020,137(9):48412
Flexible film with both piezoelectric and dielectric properties is considered to be a potential candidate for the energy conversion and storage devices. In this study, the Li+ and H2O modified sepiolite/poly(vinylidene fluoride-co-hexafluoropropylene) (LiSEP-H2O/PVDF-HFP) composite films with both good piezoelectric and dielectric properties were prepared by traditional coating process. When the H2O content was 13 wt %, the LiSEP-H2O/PVDF-HFP composite exhibited high d33 of 32 and dielectric constant of 48. Moreover, the effects of the Li+ and adsorbed H2O on the d33, F(β), dielectric constant, short-circuit currents were discussed. The adsorbed H2O enhanced the β-phase by the hydrogen bonds and Li+ improved the polarization to realize the composite film with increased piezoelectric and dielectric properties respectively. We expected the common modification to lead other clay minerals realizing the future applications in the adjustment of composites' electric properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48412. 相似文献