Surface Of Piezoelectric Material Research Articles

Research progress in enhancement strategies and mechanisms of piezo-electro-chemical coupling

Piezoelectric materials can harvest tiny mechanical energy existing in the environment, and have strong ability to convert mechanical signals into electrical signals. Piezo-electro-chemical coupling can be realized via combining piezoelectric effect of piezoelectric materials with electrochemical redox effect. In recent years, piezo-electro-chemical coupling has attracted a lot of attention from researchers in harvesting vibration energy to treat dye wastewater. The piezoelectric catalyst material dispersed in solution is deformed by ultrasonic vibrations. Owing to the piezoelectric effect and spontaneous polarization effects, positive and negative charges are generated at both ends of the catalyst, which can further react with dissolved oxygen and hydroxide ions in the solution to generate superoxide and hydroxyl radicals (·<inline-formula><tex-math id="Z-20230421141915">\begin{document}${}{\rm{O}}_2^- $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20222078_Z-20230421141915.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20222078_Z-20230421141915.png"/></alternatives></inline-formula> and ·OH) for decomposing organic dyes. However, ordinary piezoelectric catalytic materials are often difficult to meet people's pursuit of efficient treatment of organic dyes. Researchers have conducted a lot of researches on piezo-electro-chemical coupling, mainly focusing on the following two aspects: 1) the modification of piezoelectric catalysts to achieve extended carrier lifetime, accelerate carrier separation and high piezoelectric coefficients, and 2) the combination of piezo-electro-chemical coupling with photocatalysis to suppress photogenerated carrier compounding to obtain high synergistic catalytic performance. In this work, the following five strategies to enhance the piezo-electro-chemical coupling via modifying piezoelectric catalyst materials are introduced. The heterojunction structure is constructed to promote the separation of electron-hole pairs. The precious metal is coated on the surface of the catalyst to accelerate the transport and transfer of electrons. The catalyst composition is regulated and controlled to obtain an increased piezoelectric coefficient at the phase boundary. Carbon or graphene are mixed in the catalyst to accelerate the electron transfer on the surface of piezoelectric material. The number of active sites increases through introducing defects into the catalyst to increase the concentration of carriers. The physical mechanisms of five different strategies are described from the perspectives of electron transport and transfer, phase transition, and oxygen vacancies. In addition, the prospects for piezo-electro-chemical coupling in energy and biomedical applications such as hydrogen production, carbon dioxide reduction, tumor therapy and tooth whitening are presented.

Bluetooth sneaker with Arduino embedded in it based on lattice structure

Energy crisis has become a worldwide problem, and clean energy, new energy and renewable energy are the focus of attention today. With the continuous improvement of people's living standards, more and more people participate in fitness. At this time, the stampede pressure generated by human walking will be a form of energy dissipation. Secondly, people's pursuit of quality of life is also increasing day by day, in the process of daily walking shoes are expected to have massage, temperature regulation and other multi-functional characteristics. According to the existing survey, this kind of shoes with multi-function is more attractive in the market, and it is easier to get the unanimous praise of consumers. This kind of multifunctional sports shoes takes into account the various possibilities of people when they are exercising. Under the basic conditions of ensuring safety, they pay more attention to comfort and save energy, giving full play to the maximum function of sports shoes. However, the current research and development of multi-functional sports shoes need to use the battery for power supply, the function is not perfect, large quality, low efficiency of electromechanical conversion and independent load and power generation function, so there is an urgent need for a high-efficiency intelligent sports shoes to meet the needs of the market. People in the process of walking, the foot will have corresponding pressure on the soles, namely the vibration source produces vibration, and multi-functional sports shoes mainly through the matrix collection equipment energy collection, when the lattice structure, piezoelectric material deformation and generate electric field, on the surface of piezoelectric materials under vibration force can reduce charge spacing, polarization is reduced, at this point, electric current can be generated by connecting wires, thus realizing the conversion of mechanical energy into electrical energy, which can power the graphene heating plate.

Piezo-activation of peroxymonosulfate for benzothiazole removal in water

Piezoelectricity, as a kind of physical phenomenon, is a coupling between a material’s mechanical and electrical behavior. Herein, the local accumulated charges on the surface of piezoelectric material were used to break OO bond of peroxymonosulfate (PMS) to induce its activation for the benzothiazole (BTH) removal. Taking BaTiO3 as a model piezocatalyst, up to 97 % of BTH was degraded within 30 min in BaTiO3/PMS/force system, which was respective 40 %, 79 %, 83 % higher than that in BaTiO3/force piezocatalysis, force/PMS oxidation, and BaTiO3/PMS adsorption. A significant synergistic effect was observed since the reaction rate constant of BaTiO3/PMS/force was 3 times higher than the sum of those later three processes. The possible activated mechanism was proposed based on reactive species analysis, DFT calculation and LCMS determination. The stability of the piezocatalyst and the treatment performance for real wastewater were studied to investigate the potential in practical applicability. All the results demonstrated that the BaTiO3 piezoelectricity can efficiently activate PMS to enhance BTH removal, which is a promising strategy for PMS activation, as well as a valuable insight for the piezoelectrical application in wastewater remediation.

Two electrically-conducting stamps on the surface of piezoelectric materials

A model of two electrically-conducting stamps acting on the surface of piezoelectric materials is developed by using the generalized Almansi’s theorem. General solutions for distinctive or repeated eigenvalues are given. A system of singular integral equations is obtained and solved analytically. Explicit expressions for two flat, electrically conducting stamps with constant electric potential and non-constant electric potential are presented, which are valid for general cases since the present method is feasible for general cases. Numerical analyses were performed to reveal the effect of the distance between the two flat stamps on the contact behavior and to show the validity of the present derivation. The present work is very promising for FEM or BEM simulation of piezoelectric materials.

Surface acoustic wave scattering from steps, grooves, and strips on piezoelectric substrates

The paper studies, by the finite element method, the reflection of surface acoustic waves from single obstacles of regular shapes on the surface of piezoelectric materials. The so-called perfectly matched layer is used to truncate the computational domain. The following types of imperfections are considered: single steps, grooves, and projections, as well as metallic strips overlaying the substrate or inset into it. The absolute values and the phases of the reflection coefficients are computed for YZ and 128°YX LiNbO3 substrates as functions of the height-to-wavelength and the width-to-wavelength ratios. In addition, the reflectivity of gratings comprising a finite number of grooves or electrodes is computed and compared with the analytic estimations based on the coupling-of-modes theory.

Excitation of bulk elastic waves from the surfaces of piezocrystals with 3m symmetry

We have used the method of successive approximations to solve the problem of exciting bulk elastic waves from the surfaces of piezoelectric materials with 3m symmetry. In the approximation of a given electric field created by a two-electrode transducer on the surface of a piezoelectric sample, we found the displacement distribution of acoustic modes excited by the transducer. We determined the parameters for an equivalent circuit of a two-electrode transmitter, taking into account piezo additions and losses during the transformation for the surface piezotransducer deposited on 135o Y-cut lithium niobate. We show that it is possible to use surface transducers in acousto-optic modulators in the UHF region.

Acoustic Surface Waves in Split Strip Periodic Metal Gratings on a Piezoelectric Surface

Ahrruct-The propagation of acoustic surface waves in configurations of split periodic metal gratings on the surfaces of piezoelectric materials is analyzed. The analysis is based on analytic solutions for the electric field distribution. Particular attention is paid to the details of the dis- persion relations near the resonances, where the stopband frequencies for various combinations of externally interconnected or disconnected strips are calculated as functions of strip geometry for stopbands of various order. several wavelengths is frequently used either to create multiple passbands or to minimize phase errors and bulk wave conver- sion which may be a problem, especially at high frequencies. So far the models used to analyze these transducers have been equivalent circuits with adjustable empirical parameters for the effective coupling coefficient, as well as for the electrostatic coupling between distantly spaced neighboring taps. The subject of the present paper is a field analysis of split strip periodic gratings with two metal strips per period. The analysis leads to analytic expressions for the dispersion rela- tions. Particular emphasis is paid to the behavior around the stopbands where the period of the structure is close to an in- tegral number of half wavelengths. From the dispersion rela- tion one can easily derive the decay of waves in the stopbands, a figure which is of central importance in the design of surface wave resonators. Numerical results are given for the promi- nent cases with one half wavelength between neighboring strips to show the effect of thinning as well as for a regular array with four strips per wavelength corresponding to the split finger transducer. models can be derived from the dispersion relations and the field solutions without the necessity of empirically adjustable parameters. In an accompanying paper, it is shown that equivalent circuit