共查询到20条相似文献,搜索用时 31 毫秒
1.
Kuznetsova IE Zaitsev BD Joshi SG Borodina IA 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2001,48(1):322-328
The general properties of fundamental antisymmetric A0, symmetric S0, and shear horizontal SH0 acoustic waves propagating in thin piezoelectric plates have been theoretically investigated on samples of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3). The results obtained will be useful for a proper development of various physical, chemical, and biological sensors and devices for signal processing based on plate acoustic waves. 相似文献
2.
Kuznetsova IE Zaitsev BD Teplykh AA Joshi SG Kuznetsova AS 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(9):1984-1991
The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A0) and quasi-symmetric (S0) Lamb waves as well as quasi-shear-horizontal (SH0) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S0 and SH0 wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers. 相似文献
3.
Reflection of plate acoustic waves produced by a periodic array of mechanical load strips or grooves 总被引:1,自引:0,他引:1
Joshi SG Zaitsev BD Kuznetsova IE 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2002,49(12):1730-1734
The reflection of fundamental acoustic waves propagating in a thin piezoelectric plate by a periodic array of conducting strips of finite thickness or grooves has been theoretically and experimentally investigated. The analysis has shown that electrical shorting and mass loading affect the relationship of neighboring region impedances in a contrary manner. In some cases, these effects are comparable, and there exists a certain strip thickness for each piezoactive fundamental plate mode at which the reflection coefficient can become zero. A high efficiency of grooved reflector for plate acoustic waves was theoretically revealed. Experimental results for mass loading and grooved reflections, which have been obtained for an SH/sub 0/ wave propagating in the Y-X lithium niobate plate, are in a good agreement with the theory. They show a high efficiency of such reflectors and confirm the validity of using a model based on an equivalent circuit for the analysis of their operation. Investigations indicate that nearly 100% reflection of the SH/sub 0/ wave in the lithium niobate plate can be obtained with the use of a mass loading reflector containing 10 silver strips of thickness d/h=0.08 or a grooved reflector containing eight grooves of depth d/h=0.25. Here h is the plate thickness and d is the reflector thickness or depth. 相似文献
4.
Yu Jin Joshi S.G. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(3):491-494
It is found that an acoustic wave which is nearly polarized in the shear horizontal (SH) direction can propagate along the X axis of a Z-cut lithium niobate plate if the ratio h/λ, where h=plate thickness and λ=acoustic wavelength, is less than about 0.5. Attractive properties of this quasi-SH wave include: (1) phase velocity nearly constant for all values of h/λ; (2) ability to propagate in contact with a liquid medium; and (3) electromechanical coupling coefficient as high as 0.15. These properties make the wave attractive for use in a variety of sensor and signal processing applications. An example of sensor applications is illustrated by using the wave to measure conductivity of liquids (aqueous KCl solution). The frequency of a 12-MHz quasi-SH mode oscillator fabricated on a 0.48 wavelength thick Z-X lithium niobate plate is found to vary by more than 80 kHz for variation in KCI concentration from 0 to 0.15% 相似文献
5.
I. E. Kuznetsova B. D. Zaĭtsev A. A. Teplykh S. G. Joshi 《Technical Physics Letters》2006,32(12):1033-1035
The anisotropy of the angle between the phase and group velocity (power flow angle, PFA) as well as the influence of electrical boundary conditions on this angle have been studied for shear-horizontal fundamental (SH0) acoustic waves in thin piezoelectric plates of lithium niobate (LNO) and potassium niobate (KNO). Both LNO and KNO crystals possess orientations at which the PFA for SH0 waves reaches large values (17° and 48°, respectively). It is established that metallization of the piezoelectric plate surface can significantly change PFA values, in particular, by 18° and 55° for Y-X + 25° cut plates of LNO and KNO, respectively. 相似文献
6.
Yu Jin Joshi S.G. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1994,41(2):279-283
The characteristics of ultrasonic Lamb waves propagating along the X-direction of a 128° rotated Y-cut lithium niobate plate are investigated. The first higher-order antisymmetric mode, the A1 mode, is found to exhibit an anomalous behavior. The velocity of this mode remains nearly constant for all values of h/λ, where h is the plate thickness and λ is the acoustic wavelength. The particle displacement of the mode tends towards that of a pure shear horizontal (SH) wave as the ratio h/λ tends to zero. The electromechanical coupling coefficient of the wave has a value of k2=0.78×10-2 at h/λ≅0. The coupling decreases as h/λ increases, becoming negligible for h/λ>1. The velocity and coupling coefficient of the mode have been measured for various values of h/λ, and are found to be in fair agreement with theoretical calculations 相似文献
7.
Borodina I. A. Zaitsev B. D. Kuznetsova I. E. Teplykh A. A. Shurygin V. V. 《Technical Physics Letters》2003,29(9):781-783
The conditions for hybridization of the zero-order and high-order acoustic waves propagating in a piezoelectric crystal plate have been studied. The dependence of the phase velocity of the hybrid waves on the parameter hf (h is the plate thickness and f is the wave frequency) is established for the potassium niobate and lithium niobate plates possessing various crystallographic orientations and conductivities. It is found that hybridization takes place when the conductivity of a thin surface layer exceeds a certain critical value, which can vary within broad limits depending on the plate material and orientation. The degree of dispersive repulsion of the coupled modes grows with increasing electromechanical coupling coefficient. 相似文献
8.
New method of change in temperature coefficient delay of acoustic waves in thin piezoelectric plates
Zaitsev BD Kuznetsova IE Joshi SG Kuznetsova AS 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(11):2113-2120
As is well-known, the development of high-effective and thermostable acoustic devices assumes using the acoustic waves with high coefficient of electromechanical coupling (K2) and low temperature coefficient of delay (TCD). At present, it also is well-known that fundamental shear horizontal (SH0) acoustic waves in thin piezoelectric plates possess by significantly more electromechanical coupling compared to surface acoustic waves (SAW) in the same material. However, although the value of TCD of SH0 waves is insignificantly less than for SAW, this is not enough for development of thermostable devices. This paper suggests a new way of decreasing TCD of SH0 waves in piezoelectric plates at a high level of electromechanical coupling. This way assumes to use the structure containing the piezoelectric plate and liquid with the special dependence of permittivity on temperature. Theoretical and experimental investigation showed that, for SH0 wave in YX LiNbO3 plate at hf = 700 m/s (h = plate thickness, f = wave frequency) the presence of butyl acetate can decrease the value of TCD by six times at K2 = 30%. In a whole the obtained results open the wide prospect of using SH0 wave in thin piezoelectric plate for development of high effective and thermo-stable acoustic devices. 相似文献
9.
B. D. Zaitsev I. E. Kuznetsova A. M. Shikhabudinov A. A. Vasil’ev 《Technical Physics Letters》2011,37(6):503-506
A new method of parasitic mode suppression in piezoelectric resonators with transverse (lateral) electric field is described, which employs the partial coverage of electrodes by a damping layer. The potential of the proposed method is demonstrated for a resonator based on an X-cut lithium niobate plate. It is experimentally confirmed that an acoustic wave with transverse electric polarization exhibits stiffening, the degree of which depends on both the electromechanical coupling coefficient and the wave aperture 相似文献
10.
Chou CH Khuri-Yakub BT 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1989,36(3):337-341
In order to design a mixed-mode transducer with high efficiency and broad bandwidth for both longitudinal and shear wave modes, a theory is developed to determine the properties of this transducer with arbitrary acoustic loads at both ends of the piezoelectric element. Several Y-cut lithium niobate (LiNbO(3)) transducers were made on both [110] single-crystal bismuth germanium oxide (Bi(12)GeO(20)) and fused quartz. The piezoelectric plates were attached to indium bonding and later polished to operate in the 100-MHz frequency range. The experimental data of round-trip insertion loss for both longitudinal and shear modes showed an excellent agreement with theoretical predictions. 相似文献
11.
We report on the theoretical study of lithium niobate slab and wire waveguides with different kinds of cladding (silicon dioxide, sapphire and air). The mode propagation, the light confinement and radiation losses are simulated using a software based on a beam propagation method. We propose from those results lithium niobate waveguide geometries for optical integrated applications. 相似文献
12.
A. V. Golenishchev-Kutuzov V. A. Golenishchev-Kutuzov R. I. Kalimullin A. A. Potapov 《Technical Physics Letters》2012,38(9):825-827
The possibility of using photoinduced domain structures formed in lithium niobate crystals as a basis for tunable high-frequency spatial resonators of surface and bulk acoustic waves is demonstrated. 相似文献
13.
Koskela J Plessky VP Salomaa MM 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1998,45(2):439-449
We discuss effects on the propagation of surface acoustic waves (SAW) due to heavy mass loading on Y-cut lithium niobate and lithium tantalate substrates. An abrupt reduction in the leaky-SAW (LSAW) attenuation is observed in the measured admittance of a long resonator test structure on 64 degrees -YX-cut lithium niobate for aluminum electrodes of thickness h/lambda(0) beyond 9-10%. This experimental fact is explained theoretically as the slowing down of the leaky wave below the velocity of the slow shear surface-skimming bulk wave (SSBW), such that energy dissipation into bulk-wave emission becomes inhibited. An infinite transducer structure is modeled using the periodic Green's function and the boundary-element method (BEM); the computed theoretical properties well explain for the experimental findings. The model is further employed to quantify the leaky surface-wave attenuation characteristics as functions of the crystal-cut angle and the thickness of the electrodes. The resonance and antiresonance frequencies and the corresponding Q values are investigated to facilitate the selection of crystal cuts and electrode thicknesses. The transformation of the leaky SAW into a SAW-type nonleaky wave is also predicted to occur for gold electrodes, with considerably thinner finger structures. 相似文献
14.
A. A. Kolotyrin D. A. Zimnyakov E. L. Nikishin R. A. Zdrazhevskii S. V. Zavarin 《Technical Physics Letters》2011,37(11):992-995
A new method is proposed for imaging spatially inhomogeneous acoustic fields. The approach is based on the Fourier transform
of a coherent light field formed as a result of the Bragg diffraction of a probing laser beam on an ensemble of quasi-plane
acoustic waves in a lithium niobate crystal. These waves appear as a result of the transformation of an imaged acoustic field
by a spherical acoustic lens. The proposed method has been experimentally verified using model multielement acoustic sources. 相似文献
15.
I. A. Borodina I. E. Kuznetsova B. D. Zaitsev S. G. Joshi 《Technical Physics Letters》2002,28(1):10-12
The effect of light on the characteristics of an acoustic wave with the transverse-horizontal polarization (SH0) propagating in a piezoelectric plate-photoconducting layer structure was theoretically studied. Applied to the case of an Y-X cut lithium niobate (or Y-X potassium niobate) plate coated by a cadmium sulfide layer with the thicknesses h 1 and h 2, respectively, the results of this analysis show that the photosensitivity of such structures strongly depends on the h 1 and h 2 values, reaching a maximum for h 1=0.1λ and h 2=0.01λ (where λ is the acoustic wavelength). In the lithium niobate based structure with these parameters, the maximum value of the relative change in the wave velocity in response to the illumination intensity variation from 0.1 to 106 lx is 16% at a maximum damping rate of 5 dB/λ; the analogous values for potassium niobate are 47% and 17 dB/λ. These results show good prospects for the use of such a piezoelectric plate-photoconducting layer structures in photodetectors and optical radiation sensors. 相似文献
16.
Robbins WP Mueller RK Rudd E 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1988,35(4):477-483
The use of surface acoustic waves in a scanning laser acoustic microscope for the characterization of the mechanical or acoustic properties of thin films deposited on piezoelectric substrates is demonstrated. Quantitative measurements of mass loading effects of 5000-A-thick tungsten films deposited on lithium niobate substrates were obtained using 100-MHz surface acoustic waves. No information about the tungsten film could be obtained using 100-MHz compressional waves. Methods of generating surface waves on nonpiezoelectric materials so that this technique could be used on arbitrary substrates are discussed. 相似文献
17.
S. G. Joshi B. D. Zaitsev I. E. Kuznetsova I. A. Borodina 《Technical Physics Letters》1999,25(4):324-325
The characteristics of antisymmetric and symmetric Lamb waves, as well as quasi-shear-horizontal waves, propagating in thin
potassium niobate plates are investigated theoretically. It is found that the square of the electromechanical coupling coefficient
of acoustic waves in such plates can reach 100% in certain directions. The results obtained indicate that potassium niobate
is a highly promising material for creating various acoustoelectronic devices.
Pis’ma Zh. Tekh. Fiz. 25, 67–70 (April 26, 1999) 相似文献
18.
19.
N. L. Batanova A. V. Golenishchev-Kutuzov V. A. Golenishchev-Kutuzov R. I. Kalimullin A. E. Usachev 《Technical Physics Letters》2009,35(2):151-153
It is experimentally demonstrated that photoinduced gratings in lithium niobate single crystals can be used as tunable high-frequency
resonators for the surface and bulk acoustic waves. The resonance frequency can be tuned within broad limits by rewriting
gratings with interfering laser beams. 相似文献
20.
本研究基于密度泛函理论的第一性原理超软赝势平面方法计算了LiNbO3和LiTaO3的晶格参数、电子结构和弹性常数, 并利用Christoffel方程研究了二者平面声波特征。结果表明: 两者的理论计算晶格参数和弹性常数与实验值接近, 禁带宽度分别为3.78和3.98 eV, 导带底和价带顶主要由O-2p和Nb-4d(Ta-5d)态电子贡献。化学键理论揭示Li和Nb(Ta)与O原子之间有两种成键类型。 电荷布局分析结果显示有两种相应的重叠布居数, Nb(Ta)-O键呈现强共价键作用, 并且Nb-O(Ta-O)键长小于Li-O键长。LiNbO3和LiTaO3晶体平面声波有两支横波和一支纵波, 纵波速度大于横波速度, 在xy平面呈现六重对称性, 在xz和yz平面各向异性程度强于xy平面, 沿[001]、晶向上两支横波振动速度相等。最后利用模守恒赝势(Norm-conserving)计算了介电常数和静态折射率, 计算表明LiNbO3晶体的折射性能和非寻常光(e光)离散程度均强于LiTaO3晶体。 相似文献