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1.
ZnO thin film was deposited on various metal electrodes by reactive sputtering, and c-axis preferred orientation of the film has been studied. ZnO, which has high piezoelectricity, is promising for oscillators or filter devices such as surface acoustic wave (SAW) device, gas sensor, and film bulk acoustic resonator (FBAR). But, for the application of ZnO film for these devices, the film should be grown with c-axis normal to the electrode. In this study, Pt, Al, and Au were deposited on Si wafer, and the surface roughness and crystal structure of the ZnO film on the electrode were investigated using AFM, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Columnar structures of ZnO films were grown with c-axis normal to all electrodes, and among them Pt electrode showed the highest preferred orientation of ZnO film. 相似文献
2.
3.
This paper presents a multi-region Trefftz boundary element method for fracture analysis in plane piezoelectricity. To model
the sub-region that contains the crack, a special set of Trefftz functions that satisfy the traction-free and charge-free
conditions along the crack faces are constructed. To model the remaining sub-regions, the basic set of Trefftz functions co-derived
previously by the authors are employed. With the two sets of Trefftz functions, the multi-region Trefftz boundary element
method is formulated by point collocation. The special set of Trefftz functions exempts all the boundary treatment of the
crack faces and enables the direct determination of the electromechanical intensity factors. Numerical examples are presented
to illustrate the efficacy of the formulation. 相似文献
4.
Holger Fritze 《Journal of Electroceramics》2006,17(2-4):625-630
Langasite (La3Ga5SiO14, LGS) and gallium orthophosphate (GaPO4) resonators exhibit piezoelectrically exited bulk acoustic waves at temperatures of up to at least 1400∘C and 900∘C, respectively. Their mass sensitivity at elevated temperatures has been found to be about as high as that of quartz at room
temperature. Within its operation temperature range, GaPO4 shows significantly lower losses than LGS.
Factors restricting application relevant properties of LGS at elevated temperatures, such as the mass resolution, include
excessive viscous damping. Therefore, the effective viscosity is determined as a function of the temperature by fitting the
calculated complex impedance to the experimental data in the vicinity of the resonance frequency. The viscosity shows an Arrhenius-like
behavior if a temperature independent contribution is subtracted. The activation energies of the viscosity for LGS and GaPO4 correspond to those of the bulk electrical conductivity for each material. Viscosity and conductivity are obviously correlated.
Therefore, it is highly likely that the predominant conductivity mechanism also controls the mechanical damping. First attempts
to minimize the viscosity of LGS by doping are undertaken. Very light doping does, however, not change the conductivity and
viscosity of LGS. Higher doping levels have to be applied and tested.
Based on the electromechanical properties given for undoped LGS, the applicability of this material as resonant gas sensor
at 600∘C is demonstrated. 相似文献
5.
采用神经网络补偿压电陀螺的零位温漂 总被引:1,自引:0,他引:1
针对中低精度的压电陀螺静态零位输出随温度漂移严重的问题,分析了产生的原因,做了相应的实验,提出了用BP神经网络进行补偿的方法。该方法具有很强的非线性映射能力,减少压电陀螺的零位输出误差,并且将实验结果与传统的方法的结果进行比较,实验证明,在不改变陀螺结构的情况下,该方法能有效地将陀螺的静态零位温漂误差减小一个数量级以上,从而使该类型陀螺能够应用于中高精度系统中。 相似文献
6.
High energy X-ray diffraction was employed to probe the complex constitutive behavior of a polycrystalline ferroelectric material in various sample orientations. Pb(Zn,Nb)O3-Pb(Zr,Ti)O3 (PZN-PZT) ceramics were subjected to a cyclic bipolar electric field while diffraction patterns were taken. Using transmission geometry and a two-dimensional detector, lattice strain and texture evolution (domain switching) were measured in multiple sample directions simultaneously. In addition, texture analysis suggests that non-180° domain switching is coupled with lattice strain evolution during uniaxial electrical loading. As a result of this material’s high strain anisotropy, the full-pattern Rietveld method was inadequate to analyze the diffraction data. Instead, a modified Rietveld method, which includes an elastic anisotropy term, yielded significant improvements in the data analysis results. 相似文献
7.
《Journal of the European Ceramic Society》2014,34(15):3675-3683
The microstructure, electric-field-induced strain, polarization, and dielectric permittivity in (Bi0.5Na0.5)0.945−x(Bi0.2Sr0.7□0.1)xBa0.055TiO3 (BNBT–xBST) (0 ≤ x ≤ 0.08) electroceramics are investigated. An irreversible transition from rhombohedral and monoclinic coexistence phase to single rhombohedral phase is indicated with the remnant strain Sr = 0.330% at x = 0. As the BST content increases, the ferroelectric order is disrupted resulting in a degradation of the remnant polarization, coercive field, and the ferroelectric-to-relaxor transition temperature (TF–R). The coexistence of ferroelectric relaxor and ferroelectric phase is observed for the optimum composition x = 0.02 at ambient temperature with a large strain of 0.428% at 60 kV/cm (normalized strain Smax/Emax = 713 pm/V). The large strain is contributed by both ferroelectric domain reorientation behavior and the reversible relaxor to ferroelectric phase transition. 相似文献
8.
《Ceramics International》2020,46(8):12023-12030
As a core component of 2D ultrasound transducers, honeycomb-shaped 1–3 connectivity piezoelectric micropillar arrays have attracted enormous attention due to their unique performance and functionality. In this paper, honeycomb-shaped 1–3 connectivity piezoelectric micropillar arrays with a high aspect-ratio were designed and fabricated by means of deep X-ray lithography and powder injection molding in six steps: preparation of lost mold, powder-binder mixing, injection molding and demolding, removal of binders, and densification of powder. A polymer-based lost mold insert was generated by a synchrotron X-ray exposure and development process. The optimal volumetric ratio between the piezoelectric powder and binders was determined by torque rheology behavior, then they were homogeneously mixed with a twin extruder mixer. To fully fill in the micro-cavities of the lost mold, rheological properties of the mixture were analyzed with a capillary rheometer using different shear rates (50–5000 s−1) and temperatures (140 °C, 150 °C, and 160 °C). After the mixture was completely injected, the lost mold was chemically dissolved in acetone and rinsed in methanol without bending or clustering of the micropillar arrays during evaporation. The binders in the injection molded portion were thermally decomposed using a continuous heating schedule of 200 °C, 390 °C, and 600 °C in argon gas under atmospheric conditions. Finally, the particles in the sample were densified into a coherent, solid mass by eliminating pores at 1300 °C. Based on the proposed micro-manufacturing process, defect-free honeycomb-shaped 1–3 connectivity piezoelectric micropillar arrays with a pattern dimension of 42 μm and aspect-ratio of 5 were successfully produced. 相似文献
9.
10.
Lead-free piezoelectric ceramics (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 have been synthesized by traditional ceramics process without cold-isostatic pressing. The effect of the content of LiNbO3 and the sintering temperature on the phase structure, the microstructure and piezoelectric properties of (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 ceramics were investigated. The result shows that the phase structure transforms from the orthorhombic phase to tetragonal phase with the increase of the content of LiNbO3, and the orthorhombic and tetragonal phase co-exist in (K0.5Na0.5)NbO3-LiNbO3 ceramics when the content of LiNbO3 is about 0.06 mol. The sintering temperature of (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 decreases with the increase of the content of LiNbO3. The optimum composition for (1 − x)(K0.5Na0.5)NbO3-xLiNbO3 ceramics is 0.94(K0.5Na0.5)NbO3-0.06LiNbO3. The optimum sintering temperature of 0.94(K0.5Na0.5)NbO3-0.06LiNbO3 ceramics is 1080 °C. Piezoelectric properties of 0.94 (K0.5Na0.5)NbO3-0.06LiNbO3 ceramics under the optimum sintering temperature are piezoelectric constant d33 of 215 pC/N, planar electromechanical coupling factor kp of 0.41, thickness electromechanical coupling factor kt of 0.48, the mechanical quality factor Qm of 80, the dielectric constant of 530 and the Curie temperature Tc = 450 °C, respectively. The results indicate that 0.94(K0.5Na0.5)NbO3-0.06LiNbO3 piezoelectric ceramics is a promising candidate for lead-free piezoelectric ceramics. 相似文献