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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.
Fabrication and characterization of potassium-sodium niobate piezoelectric ceramics by spark-plasma-sintering method 总被引:1,自引:0,他引:1
High density (Na1−xKx)NbO3 (x = 0.5, 0.6, and 0.7) ceramics were successfully prepared by spark-plasma-sintering (SPS) method. The dielectric and piezoelectric properties of the SPS samples were investigated and compared to that of hot-pressed samples. It is found that, the SPS-sintered (Na1−xKx)NbO3 samples show higher room temperature dielectric constant, higher coercive fields, lower remnant polarizations and lower electromechanical coefficients than that of the hot-pressed (Na1−xKx)NbO3 samples. The dielectric and piezoelectric property differences between the SPS-sintered and hot-pressed samples have been attributed to grain size effects. 相似文献
7.
The crystals (dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol [DMAPNP] suitable for NLO applications were grown by the slow cooling method. The solubility and metastable zone width measurement of DMAPNP specimen was studied. The material crystallizes in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The ocular precision in the intact visible region was found to be good for non-linear optical claim. Quality of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of DMAPNP sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The third order nonlinear optical properties of DMAPNP crystals were premeditated by Z-scan method. Birefringence and optical homogeneity of the crystal were evaluated using modified channel spectrum method. The half wave voltage of the grown crystal deliberate from the elector optic experimentation. Photoconductivity measurement specified consummate of inducing dipoles owing to brawny incident radiation and also disclose the nonlinear activities of the grown specimen. 相似文献
8.
《Ceramics International》2017,43(16):13696-13701
This study describes the effect of Dy3+ doping of lead-free ferroelectric sodium potassium bismuth titanate ((Na0.7K0.3)0.5Bi0.5TiO3; NKBT) ceramics on their structural, optical, and vibrational properties. X-ray diffraction and Rietveld refinement analyses revealed that NKBT samples exhibited a rhombohedral perovskite structure belonging to the R3c space group, with the incorporation of Dy3+ resulting in structural parameter change and local atomic structure shift to tetragonal P4mm, as supported by the appearance of new Raman modes. Increased Dy3+ content decreased the NKBT band gap from 3.4 to 3.3 eV, which was ascribed to the introduction of Dy 4f levels between valence and conduction bands. Ferroelectric behavior studies combined with transport measurements explained the unexpected ferroelectric response weakening of Dy3+-modified NKBT by increased leakage current densities. 相似文献
9.
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
10.
Xiaojing Cheng Qian Gou Jiagang Wu Xiaopeng Wang Binyu Zhang Dingquan Xiao Jianguo Zhu Xiangjian Wang Xiaojie Lou 《Ceramics International》2014
A new phase boundary with rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries is designed in (K0.48Na0.52)NbO3 by adding Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3 (BNKLZ), where Zr4+ and (BNKL)2+ are respectively used to improve the temperature of a rhombohedral phase and to decrease the temperature of an orthorhombic–tetragonal phase coexistence. These ceramics endure several continuous phase transitions with increasing BNKLZ content, i.e., an orthorhombic phase (0≤x<0.03), orthorhombic–tetragonal phases (x=0.03), orthorhombic–tetragonal and rhombohedral–orthorhombic (O–T and R–O) phase existence (0.03<x≤0.05), a rhombohedral phase (0.05<x≤0.07). The ceramics with O–T and R–O have a better piezoelectric behavior as compared with other phases because of more polarization states, enhanced εr and Pr, and a dense microstructure. Moreover, piezoelectric properties could be further optimized by modifying their sintering and poling temperatures. As a result, the construction of O–T and R–O phase coexistence benefits the improvement of piezoelectric properties in KNN-based ceramics. 相似文献