506 results about "Electromechanical coupling coefficient" patented technology

A pit (52) is formed in a substrate comprising a silicon wafer (51) on a surface of which a silicon oxide thin layer (53) is formed. A sandwich structure (60) comprising a piezoelectric layer (62) and lower and upper electrodes (61, 63) joined to both surfaces of the piezoelectric layer is disposed so as to stride over the pit (52). The upper surface of the lower electrode (61) and the lower surface of the piezoelectric layer (62) joined to the upper surface of the lower electrode are treated so that the RMS variation of the height thereof is equal to 25 nm or less. The thickness of the lower electrode (61) is set to 150 nm or less. According to such a structure, there is provided a high-performance thin film bulk acoustic resonator which are excellent in electromechanical coupling coefficient and acoustic quality factor.

The invention discloses a piezoelectric film bulk acoustic resonator and a preparation method thereof. The resonator comprises a substrate, an air cavity, a bottom electrode layer, a piezoelectric layer and a top electrode layer, wherein grapheme is used as the electrode layers of the device; a support layer is not needed in the structure of the device, and the air cavity is formed between the grapheme bottom electrode layer and a groove of the substrate; the piezoelectric layer is arranged on the bottom electrode layer, and the top electrode layer is arranged on the piezoelectric layer. A preparation process of a sacrificial layer is adopted, so the dependence of the traditional process on high-precision chemical-mechanical polishing equipment is overcome, the grinding time is shortened, and the flat surface of sacrificial layer is quickly obtained. The piezoelectric film bulk acoustic resonator has the advantages that the structure is novel, the high Q (quality) value and high electromechanical coupling coefficient can be obtained, and the piezoelectric film bulk acoustic resonator can be applied to the manufacturing of filters, duplexes and multiplexes in subsequent radio frequency communication systems, and can also be combined with different sensitive films to manufacture high-performance sensors.

A piezoelectric layer has a multilayer structure including a tensile stress layer and a compression stress layer. The mechanical strength of the piezoelectric layer is increased to prevent the occurrence of cracks and to realize a high electromechanical coupling coefficient. An acoustic resonator 1 includes a first electrode 13 including at least one conductive layer, a piezoelectric layer 14 including a plurality of layers, the piezoelectric layer 14 being formed adjacent to the top face of the first electrode 13, and a second electrode 15 including at least one conductive layer, the second electrode 15 being formed adjacent to the top face of the piezoelectric layer 14. The piezoelectric layer 14 includes a tensile compression layer 23 in which tensile stress is present and compression stress layers 21 and 25 in which compression stress is present. The tensile stress in the tensile stress layer 23 and the compression stress in the compression stress layers 22 and 25 are adjusted to cancel each other.

A surface acoustic wave device includes a piezoelectric substrate made of LiNbO₃ having an electromechanical coupling coefficient k whose square is at least about 0.025, at least one electrode that is made of a metal whose density is greater than that of Al or an alloy primarily including the metal or that is composed of laminated films made of a metal whose density is greater than that of Al or an alloy primarily including the metal and another metal, the electrode being disposed on the piezoelectric substrate, a first insulating layer disposed in a region other than a region where the at least one electrode is disposed, the thickness of the first insulating layer being substantially equal to that of the electrode, and a second insulating layer covering the electrode and the first insulating layer. The density of the electrode is at least about 1.5 times greater than that of the first insulating layer.

A boundary acoustic wave device efficiently traps the vibrational energy of boundary acoustic waves and exhibits a high electromechanical coupling coefficient, and is consequently not affected by higher-order modes. The boundary acoustic wave device includes a first medium having piezoelectric characteristics, a non-electroconductive second medium, and a third medium through which slow transverse waves propagate at a lower acoustic velocity than slow transverse waves propagating through the first and second media. The first medium, the third medium, and the second medium are stacked in that order. An IDT is disposed between the first medium and the third medium. The IDT includes a metal layer made of a metal having a density ρ in the range of about 3000 kg/m³ to about 21500 kg/m³. The IDT has electrode fingers arranged at a pitch of λ and has a thickness H1 satisfying the relationship 0.006λ≦H1≦0.2λ, and the third medium has a thickness H2 satisfying the relationship H1<H2≦0.7λ.

The invention relates to a body wave resonator and a processing method thereof. The body wave resonator comprises an acoustic mirror arranged on or embedded in a substrate and provided with a first edge and a second edge, a dielectric layer which is arranged on the substrate and in full contact with the two edges of the acoustic mirror, a first electrode which is arranged on the acoustic mirror and composed of a first terminal part, a second terminal part and a main part which is arranged between the first and the second terminal parts, a piezoelectric layer which is arranged on the first electrode and composed of a main part, a first terminal part and a second terminal part, and a second electrode which is arranged on the piezoelectric layer and consists of a main part and a second part, wherein the main part is located above the main part of the piezoelectric layer and connected with the second part, so that the connected joint of the main part and the second part is arranged between the first edge and the second edge of the acoustic mirror, and an air gap is formed between the second part of the second electrode and the first terminal part of the piezoelectric layer. The body wave resonator has simple structure and convenient processing, and can improve the quality factor, effective electro-mechanical coupling factor and static discharge resistance capacity.

An ultrasonic probe is provided with a CMUT chip having a plurality of transducer elements that change electromechanical coupling coefficients or sensitivities in accordance with a bias voltage to transmit and receive ultrasonic waves, an electric conducting layer formed on the ultrasonic irradiation side of the CMUT chip, an acoustic lens arranged on the ultrasonic irradiation side of the CMUT chip, an insulating layer formed in the direction opposite to the ultrasonic irradiation side of the acoustic lens, a housing unit that stores the CMUT chip in which the electric conducting layer and the insulating layer are fixed with an adhesive and the acoustic lens, wherein the insulating layer is formed by the material that includes at least either silicon oxide or paraxylene to prevent a solvent of the adhesive from soaking into the adhered portion.

An inexpensive compact band rejection filter realizes a high sharpness of a filter characteristic at ends of passbands and has a large attenuation. In the band rejection filter, at least one of a plurality of elastic wave resonators, which contributes to formation of a transition band, has a propagation angle larger than those of the other elastic wave resonators. Accordingly, the at least one of the plurality of elastic wave resonators which contributes to the formation of the transition band has an electromechanical coupling coefficient that is smaller than electromechanical coupling coefficients of the other elastic wave resonators.

A reliable SAW device has excellent reflection and a small size, which is achieved by reducing the number of fingers defining reflectors, such that losses due to a large electromechanical coupling coefficient are small and the film thickness of electrodes has much less effect on frequencies of the device. In the SAW device having pluralities of first fingers and second fingers, disposed on a quartz substrate, constituting an IDT for exciting SH waves and reflectors for reflecting the SH waves, respectively, the first and second fingers made mainly from Al are disposed on the ST-cut 90° X-propagation quartz substrate with the Euler angles (0°, θ, 90°±2°), wherein the angle θ is within the range of about 110° to about 150°, and a normalized film thickness (H/λ) of the fingers is within in the range of about 0.025 to about 0.135.

Provided is an ultrasonic probe including: a cMUT chip having a plurality of vibration elements whose electromechanical coupling coefficient or sensitivity is changed according to a bias voltage and transmitting and receiving ultrasonic waves; an acoustic lens arranged above the cMUT chip: and a backing layer arranged below the cMUT chip.

Electric leakage preventing means is provided at the ultrasonic wave transmission/reception surface side of the acoustic lens or between the acoustic lens and the cMUT chip.

The electric leakage preventing means is, for example, an insulating layer such as a ground layer.

By using such a structure, it is possible to provide an ultrasonic probe capable of preventing electric leakage from the ultrasonic probe to an object to be examined so as to improve the electric safety and an ultrasonic diagnostic apparatus using the probe.

The invention discloses a cascade and parallel piezoelectric composite material-based cylindrical transducer, which comprises a support with an underpan, an annular backing, an end cover and a plurality of wafers, wherein the wafers are cascade and parallel piezoelectric composite wafers, are uniformly arranged on the outer side of the annular backing along the periphery and are polarized along the radial direction of the ring; insulating washers are cushioned on and under a tubular sensitive element consisting of the backing and the wafers; the tubular sensitive element is sleeved and fastened on the underpan of the support; and the end cover is fixed at the upper end of the support and on the insulating washer on the sensitive element. The transducer adopts a multi-wafer annular array as the sensitive element, the vibration of the wafers adopts a thickness model, the working frequency is higher than the radial vibration frequency of a round tube, and the high-frequency sound wave emission can be realized; moreover, because the wafers are mode of the cascade and parallel composite material, the electro-mechanical coupling factor of the composite material is high, the frequency band thereof is broad, and the transducer has high sensitivity and broad working frequency band; therefore, the transducer has the characteristics of high frequency, high sensitivity, broad band and level omnidirection.

A class of ceramic compositions according to the formula Pb_(1-z)M_z(Mn_1/3Sb_2/3)_x(Zr_yTi_1-y)_1-xO₃ where M is selected to be either Sr or Ba, x is selected to be between 0.01 and 0.1, y is selected to be between 0.35 and 0.55, and z is selected to be between 0.01 and 0.10. In some embodiments of the above composition, one or more dopants is added to the compositions. The dopant(s) may be selected from the group comprising: PbO, CeO₂, SnO₂, Sm₂O₃, TeO₂, MoO₃, Nb₂O₅, SiO₂, CuO, CdO, HfO₂, Pr₂O₃, and mixtures thereof. The dopants can be added to the ceramic composition in individual amounts ranging from 0.01 wt % to up to 5.0 wt %. The preferred ceramic compositions exhibit one or more of the following electromechanical properties: a relative dielectric constant (ε) of between 1200 and 2000, a mechanical quality factor (Q_m) of between 1500 and 2800; a piezoelectric strain constant (d₃₃) of between 250-450 pC/N, a dielectric loss factor (tan δ) of between 0.002-0.008 and a thickness electromechanical coupling coefficient (k_t) of between 0.45 and 0.7.

The invention relates to bismuth titanate natrium-silver-barium series piezoelectric ceramics with ABO3 structure. The general equation of the compound is [Bi0.5(Na1-xAgx)0.5] _{1-yBayTiO3+aM alpha O beta (wt%), and in the equation, 0 alpha Obeta is one or plural doping oxide. The main constituent is 0-5 of Biw(Na1-x-y-zKxLiyAgz})1-wTiO3, M could be Na, K, Li, Ni, Zn, Cr, Co, Nb, Ta, Al, Cu, Fe, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, In, Y, Sc, La, Ho, Lu, Sn, Sb, Mn, Ca, Ba, Sr, Mg, Si, Bi, Ag, etc. Alpha and beta mean the M element and atomicity corresponding to the relative oxide. The sintering temperature is 1100-1200 degree centigrade, keeping for 1-4 hours. The optimal value of the compound of d33 could be over 160pC/N, kp could be over 31%, dielectric loss could be below 0.03. And the technology is stable, and it would be made from traditional technology and raw material.

The invention discloses a method for preparing film bulk acoustic wave resonator on the basis of a monocrystal AlN. The method comprises the following steps of: growing (111) an oriented monocrystal Al film on a preparation substrate by using a molecular beam epitaxial growth method; growing (002) an oriented monocrystal AlN film on the oriented monocrystal Al film by using a pulse laser deposition growth method; and depositing a layer of metallic film on the AlN film to form a Al/AlN/metal sandwich piezoelectric stack structure. The piezoelectric stack structure based on monocrystal AlN prepared by the method can be used for preparing the film bulk acoustic wave resonator. The piezoelectric performance of the monocrystal AlN film is superior to that of a polycrystal AlN piezoelectric film applied to film bulk acoustic wave resonator so that the quality factor and a valid electromechanical coupling factor of a device are increased.

The invention discloses a sodium bismuth titanate based lead-free piezoelectric ceramic and a preparation process thereof. The general formula of the piezoelectric ceramic composition is (1-x)(Na0.5Bi0.5)1-aMaTiO3-xNaNbO3, wherein, x is the mol content of NaNbO3 in a ceramic system, a is the atom number of composite ions (Na0.5Bi0.5) which are replaced by M in (Na0.5Bi0.5)TiO3, x is not less than 0 but less than 0.3, a is more than 0 but less than 0.3, and M represents divalent alkaline earth metal elements Ba, Sr and Ca. As a secondary isostatic pressing forming method is adopted in the preparation process, the piezoelectric ceramic has the advantages of simple operation, high stability and low cost; and the method helps easily obtain high-density microcrystal ceramic materials, obviously improve the piezoelectric parameter and electromechanical coupling factor of the materials, and meet the practical requirement of the piezoelectric ceramic materials used in a micro-displacement actuator.

An ultrasonic probe 10 is formed by arranging a plurality of transducers 26a to 26m for converting drive signals into ultrasonic waves to transmit the waves to an object to be inspected, and receiving ultrasonic waves generated from the object to convert the waves into electrical signals. Each of the transducers 26a to 26m has a plurality of oscillation elements 34-1 to 34-30, and each of the oscillation elements 34-1 to 34-30 has a characteristic in which the electromechanical coupling coefficient changes in accordance with the strength of the direct-current bias applied by being superposed on the drive signals. Electrodes 35, 36, and 37 of each of the oscillation elements 34-1 to 34-30 are connected to terminals 49-1 and 49-2 to which the drive signals are applied.

The invention discloses a piezoceramic material and a preparation method thereof. The piezoceramic material has the chemical general formula of Pb1-xMx(Sb1/2Nb1/2)y(Mn1/3Sb2/3)z(ZreTif)1-y-zO3+awt.%Fe2O3+bwt.%Sm2O3+cwt.%MnO2+dwt.%Al2O3, wherein M is Sr<2+> and/or Ba<2+>, x=0.02-0.1, y=0.01-0.1, z=0.01-0.1, e=0.40-0.60, f=0.40-0.60, f meets the condition that e+f=1, a=0-0.4, b=0-0.5, c=0-1.0, d=0-1.0, and the content of at most one of dopants in the four dopants including Fe2O3, Sm2O3, MnO2 and Al2O3 is equal to 0. The piezoceramic material disclosed by the invention has the main performances as follows: d33=210Pc/N, epsilon33T/epsilon0=585, tan delta=0.20%, kp=0.56, kt=0.54, and Qm=1210. Compared with a common power transmitted piezoceramic material, the piezoceramic material disclosed by the invention is lower in dielectric constant, smaller in dielectric loss and higher in mechanical quality factor and electromechanical coupling coefficient and is a power transmitted piezoceramic material with favorable performance, low dielectric constant and high mechanical quality factor.

The present invention relates to a radial vibration sandwich piezoelectric ceramic ultrasonic transducer. A piezoelectric ceramic ring is arranged between a metal inner ring and a metal outer ring, the upper end surfaces of the metal inner ring, the metal outer ring and the piezoelectric ceramic ring are in the same plane, and lower end surfaces are also in the same plane. The metal inner ring and the metal outer ring can adopt steel rings, aluminum rings, brass or purple copper rings, titanium rings, aluminum nickel copper alloy rings and titanium alloy rings. The present invention realizes the high efficiency work of a radial composite transducer through a radial prestress impressed by the inner and outer metal rings, and realizes the parameter optimization of the transducer through reasonably designing the geometry size of the inner and outer metal rings simultaneously, such as resonance frequency, frequency bandwidth as well as electromechanical coupling coefficient. The present invention can be used for the high efficiency omni-directional acoustic source underwater and all kinds of supersonic processing high efficiency supersonic source in liquid.

A boundary acoustic wave device is provided in which an increase in the conductor resistance can be suppressed and a satisfactorily high electromechanical coupling coefficient K² can be achieved even when the frequency is increased. The boundary acoustic wave device includes a first medium, a second medium, and an IDT provided therebetween. In the boundary acoustic wave device, a plane that separates the IDT into two equal parts in the thickness direction is defined as a boundary plane, the energy of boundary acoustic waves that is present at the first medium side of the boundary plane is represented by E1, and the energy that is present at the second medium side of the boundary plane is represented by E2. Furthermore, under the condition that an IDT including only the conductive layer having the highest density among the plurality of conductive layers constituting the IDT is configured so that the sound velocity of boundary acoustic waves when the IDT includes the plurality of conductive layers is equal to the sound velocity of boundary acoustic waves when the IDT includes only the conductive layer having the highest density, the energy of boundary acoustic waves that is present at the first medium side of the boundary plane is represented by E1′ and the energy that is present at the second medium side of the boundary plane is represented by E2′. In this case, the relationship E1/E2>E1′/E2′ is satisfied.

The invention provides a Bi0.5Na0.5TiO3-BaTiO3-BiMg0.5Ti0.5O3 lead-free piezoelectric ceramic material, relates to a multicomponent system lead-free piezoelectric ceramic compound and belongs to the perovskite structure piezoelectric ceramic field. The composition provided by the invention can be expressed by a general formula of xBi0.5Na0.5TiO3-yBaTiO3-zBiMg0.5Ti0.5O3, wherein the numeric area of x, y and z is indicated by the shadow area of a ternary phase diagram (the area comprises the boundary line). The lead-free piezoelectric ceramic composition further contains oxide Bi2O3; and the content of oxide Bi2O3 is 1% of the content of Bi ions in the composition. The coercive field of the system changes with the three-component system components between 20kV/cm and 40 kV/cm; the piezoelectric coefficient d33 and the electromechanical coupling coefficient Kp are increased with the increase of the value of y in the polarizable component range; d33 is unequal from 100pC/N to 170 pC/N, while Kp is from 0.1 to 0.3. Besides, the depolarization temperature of the ceramics is slightly reduced between 80 DEG C and 120 DEG C with the increase of y.