Electromechanical Resonance Research Articles

Modelling of microwave magnetoelectric effect in a laminate of ferrite and piezoelectric bimorphs

The article discusses the magnetoelectric (ME) effect in a layered structure of ferrite and two piezoelectric bimorphs. Proposed theoretical model predicts a giant microwave ME coupling at the coincidence of high-order harmonics of electromechanical resonance and ferromagnetic resonance for the ferrite. In such structures, ME interaction is known to be a result of mechanical strains. Using two piezoelectric bimorphs results in the excitation of high-order harmonic modes that are suppressed in ferrite-piezoelectric bilayers. ME coefficient of 300 V/(cm·Oe) at 5 GHz is predicted for the fifth resonance mode in the laminate of yttrium-iron garnet and two langatate bimorphs. The phenomenon can be used for the realization of ME interaction based microwave devices.

Field dependence of magnetoelectric effect in the electromechanical resonance region on the Permendur -Quartz - Permendur structures

The results of an experimental study of the field dependences of the magnetoelectric effect on three-layer Permendur-Quartz-Permendur structures in the region of electromechanical resonance are presented. It has been established that at the electromechanical resonance there exists a bias magnetic field region in that an anomalous behavior of the field dependence of the magnetoelectric coefficient are observed. This effect is explained due to the presence of the AE effect in the magnetostrictive material.

On the nonlinear dynamics of pre-stressed nanoelectromechanical resonators

Motivated by the lack of sufficient accuracy in the nonlinear dynamics of the pre-stressed nano electromechanical resonators, in the present article, the concept of the dynamic instability in the pre-stressed nanoelectromechanical resonators comprehensively is investigated while the emphasis is placed on investigating the effect of the applied electric voltage. A class of nonlinear the Mathieu–Hill equation is established to determine the bifurcations while an axial parametric load is applied to excite the system. The results emphasize that the existence of different stable states allows to occur the saddle node, the supercritical, and subcritical pitchfork bifurcations. Highlights The present article provides an example of discontinuous bifurcations in a nano electromechanical system. The present study shows that a discontinuous bifurcation is always accompanied by a jump. The bifurcations classified in the present problem are considered as discontinuous ones.

Modeling of resonant magnetoelectric response in press-fit embedded ring composite

Magnetoelectric (ME) effect is a product property arising out of the interactions between the piezoelectric and the magnetostrictive phase. Multi-phase ME composites being multifunctional materials find use in myriad of applications. In this work, epoxy free two phase and three phase embedded ring ME composites have been fabricated by the press-fit technique. For a comparative study, three phase conventional epoxy bonded ring shaped composite of same dimensions have also been fabricated. Dynamic ME experiment has been conducted at room and elevated temperatures on all the prepared composites. It is shown that the epoxy free composite by virtue of the absence of epoxy shows a better resonant ME response at all temperatures. The significance of the Electromechanical Resonance (EMR) in the resonance behavior of the composites has also been highlighted. An analytical model in cylindrical coordinate system incorporating the temperature effects on the individual composite constituents and their interface coupling has been developed based on the concentric ring approach to predict the dynamic ME behavior of the epoxy free ring composite at different temperatures. The model has been further used to study the effect of volume fraction of the constituents on the ME response.

Impact of Transduction Scaling Laws on Nanoelectromechanical Systems.

We study the electromechanical transduction in nanoelectromechanical actuators and show that the differences in scaling laws for electrical and mechanical effects lead to an overall nontrivial miniaturization behavior. In particular, the previously neglected fringing fields considerably increase electrical forces and improve the stability of nanoscale actuators. This shows that electrostatics does not pose any limitations to the miniaturization of electromechanical systems; in fact, in several respects, nanosystems outperform their microscale counterparts. As a specific example, we consider in-plane actuation of ultrathin slabs and show that devices consisting of a few layers of graphene are feasible, implying that electromechanical resonators operating beyond 40GHz are possible with currently available technology.

A Modified Iterative Automatic Method for Characterization at Shear Resonance: Case Study of Ba0.85Ca0.15Ti0.90Zr0.10O3 Eco-Piezoceramics.

Coupling between electrically excited electromechanical resonances of piezoelectric ceramics is undesirable for the purpose of their characterization, since the material models correspond to monomodal resonances. However, coupling takes place quite often and it is unavoidable at the shear resonance of standard in-plane poled and thickness-excited rectangular plates. The piezoelectric coefficient e15, the elastic compliance s55E and the dielectric permittivity component ε11S for a piezoelectric ceramic can be determined, including all losses, using the automatic iterative method of analysis of the complex impedance curves for the shear mode of an appropriated resonator. This is the non-standard, thickness-poled and longitudinally excited, shear plate. In this paper, the automatic iterative method is modified. The purpose is to be able to deal with the analysis of the impedance curves of the non-standard plate as the periodic phenomena of coupling and decoupling of the main shear resonance and other resonances takes place. This happens when the thickness of the plate is reduced, and its aspect ratio (width of the excitation (w)/thickness for poling (t)) is increased. In this process, the frequency of the shear resonance also increases and meets those of other plate modes periodically. We aim to obtain the best approach for the shear properties of near coupling and to reveal both their validity and the limitations of the thus-obtained information. Finally, we use a plate of a Ba0.85Ca0.15Ti0.90Zr0.10O3 eco-piezoceramic as a case study.

Magnetoelectric Multilayer Gallium Arsenide–Nickel–Tin–Nickel Structures

The production process is considered, and the results of a theoretical and experimental study of the magnetoelectric effect in a multilayer structure obtained by galvanic deposition of alternating layers of nickel and tin onto a gallium arsenide substrate are presented. It is experimentally found that the use of tin as an intermediate layer in a multilayer structure decreases the mechanical stresses arising from the inconsistency of the lattice parameters at the nickel/gallium arsenide interface, which makes it possible to obtain high-quality multilayer structures with the thickness of the nickel layer of about 100 μm. On the basis of the joint solution of the equations of elastodynamics and electrostatics for the magnetostriction, piezoelectric, and buffer layers, an expression for the magnetoelectric voltage coefficient is obtained. It is theoretically shown and experimentally confirmed that the frequency dependence of the magnetoelectric coefficient has a resonant character, and the value of the resonant frequency gradually decreases with the growth in the number of layers from the value corresponding to the natural oscillation frequency of a plate made of gallium arsenide, approaching the value corresponding to the natural oscillation frequency of a plate consisting of a layer of nickel and tin, the thickness of which is equal to double the thickness of the layer of nickel. It is experimentally found that, in the region of electromechanical resonance, the obtained structures have a high quality factor Q ≅ 1000, which is more than 20-fold higher than the quality factor of the magnetoelectric structures fabricated by gluing, and have good adhesion between the layers. These structures are promising for creating devices based on the magnetoelectric effect.

Magnetodielectric and magnetoelectric correlation in (1-x)PMN-PT/xCFO 0–3 particulate composites

In this work, the relationship between dielectric, ferroelectric, piezoelectric properties and the magnetoelectric coupling in (1-x)PMN-PT/xCFO multiferroic particulate composites were investigated. The magnetodielectric response showed strong frequency and CFO concentration dependence, which for composites with CFO concentration higher than 30 M%, it was reported a magnetodielectric response up to 10% around the electromechanical resonance regime for magnetic fields of 15 kOe. Additionally, at low magnetic fields a positive magnetodielectric coefficient (∼2%) associated to the magnetoelectric coupling was observed. The MD effects for particulate composites were attributed to the co-contribution of the magnetoelectric polarization, at low magnetic fields, and a compressive stress on ferroelectric phase due to magnetostriction effect, at high magnetic field.

Direct Magnetoelectric Effect in a Sandwich Structure of PZT and Magnetostrictive Amorphous Microwires.

The magnetoelectric (ME) response in a trilayer structure consisting of magnetostrictive Fe77.5B15Si17.5 amorphous microwires between two piezoelectric PZT (PbZr0.53Ti0.47O3) layers was investigated. Soft magnetic properties of wires make it possible to operate under weak bias magnetic fields below 400 A/m. Enhanced ME voltage coefficients were found when the microwires were excited by ac magnetic field of a frequency of 50–60 kHz, which corresponded to the frequency of electromechanical resonance. The as-prepared microwires were in a glass coat creating a large thermoelastic stress and forming a uniaxial magnetic anisotropy. The effect of glass-coat removal and wire annealing on ME coupling was investigated. The glass coat not only affects the wire magnetic structure but also prevents the interfacial bonding between the electric and magnetic subsystems. However, after its removal, the ME coefficient increased slightly less than 10%. Refining the micromagnetic structure and increasing the magnetostriction by stress release during wire annealing (before or after glass removal) strongly increases the ME response up to 100 mV/(cm × Oe) and reduces the characteristic DC magnetic field down to 240 A/m. Although the achieved ME coefficient is smaller than reported values for multilayered films with layers of PZT and soft magnetic alloys as Metglass, the proposed system is promising considering a small volume proportion of microwires.

Engineering Resonance Modes for Enhanced Magnetoelectric Coupling in Bilayer Laminate Composites for Energy Harvesting Applications

The magnetoelectric (ME) effect in composites, a strain-mediated coupling phenomenon between piezoelectric and magnetostrictive phases, has a wide range of technological applications. Here, ME coupling phenomena are explored in $\mathrm{Pb}$-free piezoelectric, $0.5\mathrm{Ba}({\mathrm{Zr}}_{0.2}{\mathrm{Ti}}_{0.8}){\mathrm{O}}_{3}\text{\ensuremath{-}}0.5({\mathrm{Ba}}_{0.7}{\mathrm{Ca}}_{0.3}){\mathrm{Ti}\mathrm{O}}_{3}$ and piezomagnetic ${\mathrm{Ni}\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ bilayer laminate composites. The direct and converse ME coupling strengths are found to be enhanced at the electromechanical resonance modes, rather than at the off-resonance frequencies. Here, it is proposed to further enhance the ME coupling strength at electromechanical resonance modes by the in-phase superimposition of the radial and second bending modes via varying the bilayer thickness, which, in turn, varies the volume fraction of the bilayer. The proposed enhanced ME coupling is experimentally demonstrated at a theoretically envisaged bilayer thickness of about 1.8 mm. This results in a large direct ME coupling coefficient of $22.5\phantom{\rule{0.1em}{0ex}}\mathrm{V}\phantom{\rule{0.1em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.1em}{0ex}}\mathrm{O}{\mathrm{e}}^{\ensuremath{-}1}$, which is around 100% more than the values observed at individual resonance modes. The results are further validated by calculations from theoretical models. The method adopted in this work gives a roadmap to the significant enhancement of the ME effect in laminate composites.

Simultaneous energy harvesting and vibration control in a nonlinear metastructure: A spectro-spatial analysis

Considerable attention has recently been given to the study of simultaneous energy harvesting and vibration attenuation in metastructures. However, only linear metastructures were investigated although nonlinear metastructures and nonlinear electromechanical devices offer superior interesting wave propagation phenomena (e.g., birth of solitary waves, tunable bandgap, acoustic nonreciprocity) and broadband energy harvesting. In this paper, we investigate the wave propagation in a weakly nonlinear metastructure with electromechanical resonators. Explicit expressions are derived for the nonlinear dispersion relations using the method of multiple scales. These expressions are validated via direct numerical integration. We carried out parametric studies to investigate the role of different parameters of the electromechanical resonators on the linear and nonlinear band structure. To obtain further detailed information on the nonlinear wave propagation, we employ spectro-spatial analysis on the numerical simulations. This spectro-spatial analysis can reveal the output voltage distortion due to different types of nonlinearities. The results indicate that nonlinear chain can enhance energy harvesting through the birth of solitary wave and without degrading the boundary of the bandgap. The results also suggest that such a system is suitable for designing electromechanical diodes and rectifiers.

A Portable Very Low Frequency (VLF) Communication System Based on Acoustically Actuated Magnetoelectric Antennas

A novel very low frequency (VLF) communication system using one pair of magnetoelectric (ME) antennas has been proposed. The ME antennas are strain-mediated acoustic resonators operating at their electromechanical resonance in the VLF band. The measured near-field radiation pattern reveals ME antennas are equivalent to dipole antennas. The magnetic field radiated by the ME transmitter has been predicted along with distance ranging from 1 mm to 100 km. The measured magnetic field distribution coincided well with the prediction, and the maximum communication distance of 120 m has been achieved. With 80 V driving voltage, the power consumption of the ME transmitter has been measured as 400 mW. Furthermore, the direct antenna modulation (DAM) has also been successfully demonstrated on the ME antennas.

Versatile power and energy conversion of magnetoelectric composite materials with high efficiency via electromechanical resonance

A better understanding of magnetoelectric (ME) energy materials with superior properties stimulates exploration of next generation of versatile energy devices with a high efficiency. Although a number of investigations have focused on developing multiferroic composite materials because of their potential in cutting-edge multifunctional devices, advances in basic research have not yet been translated into benefits for practical applications. In the present investigation, we introduce a two-phase magnetoelectric composite made of nanocrystalline FeBSi metallic ribbons (Metglas) and Mn3+,2+ acceptor doped Pb(Mg1/3Nb2/3)O3–Pb(Zr,Ti)O3 (PMN-PZT) single crystal, and great enhancements in ME coupling coefficient (αME~12500 V/Oe cm) with a tunable resonance frequency, current-to-voltage (I–V) conversion ratio (~15090 V/I), as well as power conversion efficiency (η ~95%) are found at the fundamental electromechanical resonance, which represent the highest values ever reported. This study also provides a fundamental understanding of the role of a figure of merit (FOM), kij,eff× Qm,eff, on ME coupling performances in ferromagnetic and ferroelectric two-phase ME composite. The enhanced performances are attributed to the laser heat treatment induced Nano crystallization in Metglas, lower magnetic and dielectric loss (tan δ), and also higher mechanical quality factor (Qm,eff) in ME composite. This research opens up the possibilities of developing ME composite materials for next-generation versatile energy and power conversion devices.

Size-dependent dynamic characteristics of graphene based multi-layer nano hetero-structures

Carbon-based nano hetero-structures are receiving increasing attention due their ability in multi-synchronous modulation of a range of mechanical and other critically desirable properties. In this paper, the vibration characteristics of two different graphene based heterostructures, graphene-hexagonal boron nitride (hBN) and graphene-molybdenum disulfide (MoS2), are explored based on atomistic finite element approach. Such vibrational characteristics of nanostructures are of utmost importance in order to access their suitability as structural members for adoption in various nano-scale devices and systems. In the current analysis, the developed atomistic finite element model for nano-heterostructures is extensively validated first with the results available in literature considering elastic responses and natural frequencies. Thereafter a range of insightful new results are presented for the dynamic behaviour of various configurations of graphene-hBN and graphene-MoS2 heterostructures including their size, chirality and boundary dependence. The investigation of tunable vibrational properties along with simultaneous modulation of other mechanical, electronic, optical, thermal and chemical attributes of such nano-heterostructures would accelerate their application as prospective candidates for manufacturing nanosensors, electromechanical resonators, and a wide range of other devices and systems across the length-scales.

Magnetoelectric Composites: Modeling and Application

The progress in electronic technology is directly coupled with the advances made in materials science. Within the broad class of materials available today, functional materials provide unique opportunity for developing novel components and devices as their physical and chemical properties. A combination of ferromagnetic and ferroelectric materials provides a new class of functional materials, termed as magnetoelectrics. An overview of modern magnetoelectric composites and examples of the design of electronic devices based on them are presented. The feature of these materials is that their parameters changes under the influence of an external magnetic and electric fields. The behavior of magnetoelectric composites in the wide frequency range is considered. Modeling of ME composites at low frequencies and in the field of electromechanical, ferromagnetic and magnetoacoustic resonances has shown that they can be effectively used to design various electronic devices in a wide frequency range. Nomographs method which can be used to plot the ME parameters versus initial material parameters and component volume fractions is presented. Nomographs can be used for a quick test of ME composites for applications where an approximate answer is appropriate and useful. Examples of ME composites application such as: magnetic field sensors, current sensors, microwave phase shifters, filters, attenuators, isolators are presented.

Performance Analysis of a Humidity Sensor based on a micro-resonator functionalized with TiO2 nanoparticles

This article proposes a novel humidity sensor based on a low-frequency micromachined electromechanical resonator functionalized with nanoparticles of TiO2 deposited on a preparation layer of Al2O3 nanoparticles. Using a low-frequency resonator allows for obtaining a better immunity to the nonidealities of the conditioning electronics components and minimizes the degradation of the resonator quality due to the deposition of the sensing material. In this article, a relationship is derived between the sensor construction parameters, the obtainable sensor resolution, and the requirements in terms of resolution and accuracy of the measurement system, showing the applicability of such sensors in the context of low-cost, low-power distributed sensing systems. An ad hoc characterization system allowed for characterizing the proposed sensor, proving that this solution is viable and requires a simple preparation route and that the sensor has satisfactory performance in a large humidity range. It was shown that the sensitivity can be increased simply by repeating the TiO2 nanoparticle deposition obtaining at least an increase of the relative sensitivity of 5 ppm/1% RH at each deposition step.

In situ steering of shear horizontal waves in a plate by a tunable electromechanical resonant elastic metasurface

A multifunctional electromechanical coupling metasurface is proposed to steer elastic shear horizontal (SH) waves. The horizontal shear deformation of the metasurface is coupled with a shunting circuit by in-plane polarized piezoelectric patches. A prospective phase distribution along the metasurface can be achieved by adjusting the negative capacitances of the shunting circuit to change the electromechanical resonant response. Multiple functions are demonstrated, including wave focusing and anomalous refraction of plane waves in different frequencies. In addition, an asymmetric wave transmission is produced by designing a dual-layer metasurface. Results show that this metasurface opens up a way toward advanced electromechanical coupling and tunable manipulation of elastic SH waves.

Исследование вибрационных характеристик обмоток тягового двигателя пульсирующего тока НБ-514

The purpose of the article is to study the vibration characteristics of the windings of NB-514 pulsed current traction motor to identify the causes of early failure of the pole windings in order to improve their reliability in operation. The amplitude-frequency characteristics of NB-514 pulsed current traction motor winding vibration are studied; the analog vibration signal is converted into a digital code, which follows by the signal processing by digital methods. To study vibration characteristics a test bench is created, which enables the measurement of amplitude and frequency characteristics of traction motor vibrations. The analysis of the obtained measurements has shown that there are electromechanical resonances with a high degree of q-factor of the compensating winding of NB-514 traction motor and connection points of its windings and the brush holder bus at the frequencies close to 100, 200, 400, 500 and 600 Hz.

Numerical Modelling of Vibration Characteristics of a Partially Metallized Micro Electromechanical System Resonator Disc

In this paper, we report an extension of a polynomial and numerical vibrational characterization of an annular piezoelectric disc resonator partially covered with electrodes. The three governing partial differential equations of motion are solved to provide the frequency response of the piezoelectric disc using a polynomial approach. This method makes use of Legendre polynomials series to express the mechanical displacement components and the electrical potential which are introduced into the equations of motion of the piezoelectric structure. The principal advantage of this method consists of incorporating the electrical source, the boundary and continuity conditions directly into the governing equations by the use of position-dependent physical constants and by a wise choice of the polynomial expansions for the independent variables, the mechanical displacement components and the electrical potential. Both harmonic and modal analyses were studied and are presented. Numerical calculations based on the foregoing method were performed to present resonance and anti-resonance frequencies, electromechanical coupling coefficient, field profiles and electrical input admittance for PIC151 and PZT5A disc resonators with various metallization rates. The high accuracy and reliability of our approach is confirmed via a comparison of our results with their counterparts reported in literature.

Stability of delocalized nonlinear vibrational modes in graphene lattice

Crystal lattices support delocalized nonlinear vibrational modes (DNVMs), which are determined solely by the lattice point symmetry, and are exact solutions of the equations of atomic motion for any interatomic potential. DNVMs are interesting for a number of reasons. In particular, DNVM instability can result in the formation of localized vibrational modes concentrating a significant part of the lattice energy. In some cases, localized vibrational modes can be obtained by imposing localizing functions upon DNVM. In this regard, stability of DNVMs is an important issue. In this paper, molecular dynamics is employed to address stability of all four delocalized modes in a graphene lattice in the presence of small perturbations both in the plane and normal to the plane of the lattice. When DNVM amplitude is above the stability threshold, atom trajectories deviate from the mode pattern exponentially in time. Critical exponents are calculated for the in- and out-of-plane displacements. Stability threshold amplitudes are established. Interestingly, in three of the studied DNVMs the in-plane displacements diverge faster, but in one of them the instability develops through the out-of-plane displacements. This result can be explained by the difference in atomic vibration patterns of DNVMs. Reported results refine our understanding of the nonlinear dynamics of graphene lattice and can be useful in the design of electro-mechanical resonators and sensors.