11 results about "Electromechanical coupling coefficient" patented technology

This invention relates to the field of piezoelectric materials technology, specifically to a chiral nitrogen-containing heterocyclic organic crystalline piezoelectric material and its preparation method. The organic crystalline piezoelectric material is N-cyanoethyl-( S )-2-methylpiperazine hydrochloride, whose core is a one-dimensional hydrogen-bonded chain construction strategy of unilaterally protonated chiral piperazine, with protonated N-cyanoethyl-( S Using 2-methylpiperazine cations as structural building blocks and chloride ions as charge balancers, a highly oriented one-dimensional hydrogen bond chain is constructed by regulating intermolecular hydrogen bonding. This enhances the ordered arrangement of molecular dipoles and optimizes the synergistic mode of lattice strain-polarization response, achieving a breakthrough in piezoelectric properties. The material exhibits a piezoelectric coefficient as high as ±80 pC / N and an electromechanical coupling coefficient as high as 0.35, far exceeding known chiral organic piezoelectric materials. Furthermore, it demonstrates excellent thermal stability and can be widely applied in demanding applications such as micro-pressure sensors, low-frequency vibration detectors, and micro energy harvesters.

This invention discloses a performance optimization method for a tristable energy harvester under low-frequency excitation based on vibration resonance, belonging to the field of energy harvester optimization. The implementation method is as follows: a standard rectifier circuit is selected as the nonlinear collection circuit and connected to the energy harvester to achieve a stable DC output; a strongly nonlinear system model of the electromechanical coupled tristable energy harvester system is established; the slow variable equation of the tristable energy harvester system is derived using the variable separation method; the steady-state solution and analytical expression of the DC power of the tristable energy harvester system are derived using the harmonic balance method; an optimization model of the tristable energy harvester system under low-frequency excitation is obtained based on vibration resonance; the influence of low-frequency excitation amplitude, low-frequency excitation frequency, stiffness coefficient, time constant ratio, and electromechanical coupling coefficient on the collection performance of the tristable energy harvester system is analyzed using the optimization model, and the optimal combination is selected to achieve efficient energy harvesting of the tristable energy harvester system under low-frequency excitation.

The application discloses an equal-potential ring capacitive micromachined ultrasonic transducer and a preparation method thereof, and belongs to the technical field of micro-electro-mechanical systems, which comprises: a residual substrate as a lower electrode; a lower insulating layer; a support for defining a cavity; a vibratable diaphragm covering above the support, which forms the cavity together with the support and the lower insulating layer; an upper insulating layer; an upper electrode formed above the upper insulating layer and projected in the cavity region; and an equal-potential ring formed above the upper insulating layer and surrounding the upper electrode, the projection of the equal-potential ring is in the support region, and the equal-potential ring is electrically insulated from the upper electrode. The application increases the equal-potential ring at the support, makes the electric field distribution more uniform and stable, reduces the edge effect and parasitic capacitance of the support region, and thus realizes a high electromechanical coupling coefficient.

This invention relates to a method for preparing and applying a type 2-3 piezoelectric composite material. The invention aims to solve the problems of low electromechanical coupling coefficient and excessively high acoustic impedance in existing traditional 2-2 piezoelectric composite materials, which lead to acoustic impedance mismatch and consequently narrow operating bandwidth and low sensitivity of ultrasonic probes. The method includes: 1. Cutting the piezoelectric material; 2. Preparing a filler epoxy resin material; 3. Casting; 4. Thickness reduction. Application: Used in the fabrication of linear phased array ultrasonic transducers.

The present application relates to a kind of PMN-PNN-PZT piezoelectric ceramic material with high Curie temperature, high piezoelectric coefficient and high electromechanical coupling coefficient and its preparation method.The chemical composition of the PMN-PNN-PZT piezoelectric ceramic material is as follows:aPb(Mg 1 / 3 Nb 2 / 3 )O3‑bPb(Ni 1 / 3Nb 2 / 3 )O3‑cPbZrO3‑dPbTiO3 (aPMN‑bPNN‑cPZ‑dPT), wherein 0.00≤a≤0.20, 0.18≤b≤0.38, 0.24≤c≤0.25, 0.37≤d≤0.38.The present application introduces lead niobium magnesium acid lead-zirconium titanate in lead niobium nickel acid lead, realizes the common improvement of Curie temperature, piezoelectric coefficient and electromechanical coupling coefficient by component design, and it has very important significance to high-temperature high-performance piezoelectric device and piezoelectric energy conversion device.

This invention relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a piezoelectric layer; and a top electrode, wherein: the piezoelectric layer comprises a first layer and a second layer, an acoustic resistive layer is disposed between the first layer and the second layer, the inner edge of the acoustic resistive layer is located inside the boundary of the acoustic mirror in the horizontal direction, the acoustic resistive layer is different from the acoustic resistive layer; and the material of the first layer is different from the material of the second layer. This invention also relates to a bulk acoustic wave resonator assembly, a method for adjusting the electromechanical coupling coefficient of a bulk acoustic wave resonator, a method for adjusting the difference in electromechanical coupling coefficients of resonators in a bulk acoustic wave resonator assembly, a filter, and an electronic device.

This invention discloses a simulation method for finite element analysis of piezoelectric material parameters, comprising the following steps: fabricating a thin-film bulk acoustic resonator; determining the dimensions of the resonator and the thickness of each layer; testing the Y11 curve of the resonator and extracting the series resonant frequency and effective electromechanical coupling coefficient; filling some parameters of the elastic matrix and coupling matrix into the material properties of the finite element simulation software, selecting stress-charge type constitutive relation in the piezoelectric material properties of the finite element analysis software; establishing a resonator model; simulating the admittance-frequency domain curve Y11 of the resonator model; comparing the measured Y11 curve of the resonator with the simulated Y11 curve, confirming the parameters in the elastic matrix of the piezoelectric material through parametric scanning based on the series resonant frequency; and determining the coupling matrix of the piezoelectric material through parametric scanning based on the effective electromechanical coupling coefficient of the resonator.

This invention provides a bulk acoustic wave resonator with adjustable electromechanical coupling coefficient and its adjustment method. The bulk acoustic wave resonator includes a piezoelectric functional layer and i electrical port groups. The piezoelectric functional layer has open sides. The i electrical port groups are arranged sequentially and at intervals along a preset direction, with equal distance between any two adjacent electrical port groups. Each electrical port group includes a first electrical port and a second electrical port. The first electrical port is located on the upper surface of the piezoelectric functional layer, and the second electrical port is located on the lower surface of the piezoelectric functional layer, directly opposite the first electrical port. This invention's bulk acoustic wave resonator with adjustable electromechanical coupling coefficient achieves dynamic adjustment of the anti-resonance frequency while maintaining a constant resonant frequency by changing the electrical connection between the first and second electrical ports located opposite each other on both sides of the piezoelectric functional layer. This allows for dynamic adjustment of the electromechanical coupling coefficient of the bulk acoustic wave resonator.

An acoustic wave device comprises a substrate including a piezoelectric material, interdigital transducer (IDT) electrodes including interdigitated electrode fingers disposed on a surface of the substrate, and a passivation layer formed on tops of the IDT electrodes and on the piezoelectric material in gaps between adjacent IDT electrodes, the passivation film being thicker on the tops of the IDT electrodes than on the piezoelectric material in the gaps between adjacent IDT electrodes to improve an electromechanical coupling factor of the acoustic wave device.

A transverse excitation bulk acoustic wave resonator and a preparation method thereof, the structure of which comprises a piezoelectric layer, a top arc-shaped double electrode, a substrate and a cavity below the piezoelectric layer, the upper surface of the piezoelectric layer is configured with an arc-shaped double electrode interdigital structure connected by a bus perpendicular to the direction of the electrode. In addition, the resonator also adopts an electrode end region aperture region etched, by using an acoustic impedance mismatch to limit the acoustic wave reflection boundary, the stray mode of the resonator can be effectively suppressed and the side acoustic energy leakage of the resonator can be reduced, and the quality factor of the resonator is improved. The design of the arc-shaped double electrode can effectively suppress the parasitic mode and improve the spectral smoothness while realizing high quality factor (Q) and high electromechanical coupling coefficient (k t 2 ), so that the filter formed thereby has excellent characteristics of large bandwidth, low loss, low power consumption and steep roll-off.

This invention discloses a high-sensitivity sensor based on lead-free piezoelectric ceramics and its application, belonging to the field of sensor technology. The high-sensitivity sensor is based on lead-free piezoelectric ceramics, and the raw material of the lead-free piezoelectric ceramics has the following general formula: (1-x)(K 1‑a Na a (Nb) 1‑b‑c Ta b Sb c O3-xBi 0.5 (Na 1‑d K d ) 0.5 (Zr 1‑e Sn e O3, where 0.02≤x≤0.04, 0.42≤a≤0.65, 0≤b≤0.06, 0.02≤c≤0.08, 0≤d≤1, 0.04≤e≤0.06. This invention uses phosphorylated chitosan and polyethylene glycol instead of traditional polyvinyl alcohol as binders to prepare multi-element doped KNN-based lead-free piezoelectric ceramics. These ceramics possess stable R-T phase boundaries, high piezoelectric constant, high electromechanical coupling coefficient, low dielectric loss, and high Curie temperature, meeting the requirements for high-sensitivity sensors.