Direct and inverse magnetoelectric effect in layered composites in electromechanical resonance range: A review

A model is presented for the increase in magnetoelectric (ME) coupling in magnetostrictive-piezoelectric bilayers in the electromechanical resonance region. The ME voltage coefficients α_E have been estimated for transverse field orientations corresponding to minimum demagnetizing fields and maximum α_E. We solved the equation of medium motion taking into account the magnetostatic and elastostatic equations, constitutive equations, Hooke's law, and boundary conditions. The resonance enhancement of ME voltage coefficient for the bilayer is obtained at antiresonance frequency. To obtain the inverse ME effect, a pick up coil wound around the sample is used to measure the ME voltage due to the change in the magnetic induction in magnetostrictive phase. The measured static magnetic field dependence of ME voltage has been attributed to the variation in the piezomagnetic coefficient for magnetic layer. The frequency dependence of the ME voltage shows a resonance character due to the longitudinal acoustic modes in piezoelectric layer. The model is applied to specific cases of cobalt ferrite–lead zirconate titanate and nickel–lead zirconate titanate bilayers. Theoretical ME voltage coefficients versus frequency profiles are in agreement with data.     

Theory of the magnetoelectric effect in ferromagnetic-piezoelectric heterostructures

A theory of the magnetoelectric effect in ferromagnetic-piezoelectric bilayer structures is considered for platelike samples. The magnetoelectric voltage coefficient is expressed through the parameters characterizing the magnetic and piezoelectric phases. It is shown that the magnetoelectric voltage coefficient considerably increases in the region of electromechanical resonance. The thickness ratio between the ferromagnetic and piezoelectric phases at which the magnetoelectric voltage coefficient is maximum is determined. The calculated magnetoelectric voltage coefficients for Permendur-PZT (lead zirconate titanate) structures are presented and compared with the experimental data.     

Influence of the Δ<Emphasis Type="Italic">E</Emphasis> Effect on the Field Dependence of the Magnetoelectric Effect in the Region of Electromechanical Resonance

The influence of the ΔE effect on the field dependence of the resonant magnetoelectric effect in bulk composite materials with a composition of ferrite nickel spinel–lead zirconate titanate has been investigated in the electromechanical resonance region. It has been shown that the field dependence of the effect is determined not only by the magnetic-field dependence of the piezomagnetic coefficient, but also by the field dependence of the Young modulus. The dependence of the resonance frequency of the effect on the bias field has been analyzed.     

Inverse magnetoelectric effect in disk-shaped samples of ferrite piezoelectric composites

A theory of the inverse magnetoelectric effect in the vicinity of electromechanical resonance in disk-shaped samples is presented. An expression for the coefficient of the inverse magnetoelectric transformation has been obtained using the effective parameter method. It has been shown that a sharp increase in the magnitude of the effect occurs at a frequency of electromechanical resonance, and the resonance frequencies for the direct and inverse magnetoelectric effects are different. The dependences of the resonance frequencies on the ferrite percentage in ferrite-nickel spinel samples and lead zirconate titanate samples have been studied experimentally.     

Ultralow-frequency magnetoelectric effect in a multilayer ferrite-piezoelectric structure

The magnetoelectric effect is experimentally studied in a multilayer nickel zinc ferrite-lead zirconate titanate structure at frequencies of 10^?3–10 Hz that is placed in a harmonically modulated magnetic field of amplitude to 1 kOe. The nonlinearity of the ferrite magnetostriction and the conductivity of the films are shown to double the frequency and distort the shape of the magnetoelectric voltage. The magnetoelectric signal amplitude decreases linearly with decreasing field modulation frequency. The feasibility of using the magnetoelectric effect to detect ultralow-frequency magnetic fields is demonstrated.     

Lead zirconate titanate-nickel zink ferrite thick-film composites: obtaining by the screen printing technique and magnetoelectric properties

Layered thick-film composites containing one lead zirconate titanate (PZT) layer, one nickel zinc ferrite (NZF) layer, two PZT-NZF layers, or three PZT-NZF-PZT layers each 40–50 μm thick are prepared. The layers are applied by screen printing on a ceramic aluminum oxide substrate with a preformed contact (conducting) layer. The dielectric properties of the composites are studied in the temperature interval 80–900 K and the frequency interval 25 Hz-1 MHz. Polarized samples exhibit piezoelectric, pyroelectric, and magnetoelectric effects. In tangentially magnetized two- and three-layer composites, the magnetoelectric conversion factor equals 57 kV/(m T) at low frequencies and reaches 2000 kV/(m T) at the mechanical resonance frequency.     

Numerical modeling of the magnetoelectric effect in magnetostrictive piezoelectric bilayers

A numerical modeling of the magnetoelectric (ME) effect in the bilayer structures lead zirconate titanate (PZT)/lanthanum strontium manganite (LSMO), PZT/nickel ferrite (NFO) and PZT/cobalt ferrite (CFO) is investigated for both static and dynamic behaviors. Mainly, this work focuses on the ME coupling of the rectangular bilayer structures at the electromechanical resonance (EMR) and predicts a resonance frequency that is found to increase with the decrease of length and the rise of PZT volume fraction. The calculated ME voltage coefficients versus frequency profiles for these three samples show a strong resonance character and the values at the EMR are about 200 times the values far from the EMR state. The estimated resonance frequencies are both at about 120 kHz for 15-mm-long NFO/PZT and CFO/PZT bilayers with PZT volume fraction v=0.25. Furthermore, the relevant experiments were carried out to verify the numerical results. PACS 75.80.+q; 75.50.Gg; 75.60.-d     

Anisotropy of Magnetoelectric Properties of Ferrite–Piezoelectric Bulk Composites

Technical Physics - The anisotropy of magnetoelectric properties of lead zirconate–titanate and nickel ferrite based bulk composites has been experimentally studied. It has been shown that a...     

2-2型PMNT/NFO复合磁电效应模拟

利用弹性力学模型,基于铁电相与铁磁相的本构方程,建立磁电复合材料的本构方程,推导2-2型非理想耦合的磁电双层、三层复合薄膜的纵向、横向磁电(ME)电压系数.研究铁磁相材料铁酸镍(NFO)和铁电相材料铌镁酸铅-钛酸铅(PMNT)复合的磁电效应,分析复合材料的磁电电压系数与PMNT体积分数、界面耦合参数、两相体积比及复合总层数的关系.结果表明两相材料的性能、体积分数以及耦合系数、复合层数都影响磁电电压系数.     

Inductance–capacitance resonance effect in the magnetoelectric composites characterization system

This paper presents the inductance–capacitance (LC) resonance effect in the magnetoelectric (ME) composites characterization system. The measured magnetoelectric voltage coefficient is significantly affected by the LC resonance at the electromechanical resonant frequency, but not at 1 kHz, typically reported in the literature. Decreasing the measuring circuit inductance and/or capacitance helps to reduce the LC resonance effect. While it is impossible to completely eliminate the coil inductance and capacitance, they should be accounted for by proper circuit balancing. One can accurately calculate the sample intrinsic ME voltage coefficient knowing L and C of the measuring circuit. This study is helpful for designing and building the ME characterization systems.     

Nonlinear magnetoelectric effect in composite multiferroics

The theoretical and experimental studies of the nonlinear magnetoelectric effect in composite multiferroics in the low-frequency spectral region and in the electromechanical resonance region have been performed. It has been shown that such structures demonstrate a nonlinear magnetoelectric effect, which is quadratic in ac magnetic field strength at weak magnetic fields. In the region of the electromechanical resonance, the resonance excitation of an electric field occurs by means of ac magnetic field at a frequency lower than the resonance frequency by a factor of two. In the low-frequency spectral region, there is a difference of amplitude values of two neighboring voltage maxima due to the superposition of signals from the linear and nonlinear effects, and the difference is proportional to the dc magnetic field strength in weak fields. The results of the experimental study of the two-layer permendur-lead zirconate titanate structure are presented.     

Wide-band magnetoelectric characterization of a ferrite-piezoelectric multilayer using a pulsed magnetic field

The use of a pulsed magnetic field for studies on frequency characteristics of the magnetoelectric (ME) effect in multilayer composite structures is described. The method is based on the excitation of a ferrite-lead zirconate titanate multilayer with short magnetic field pulses, followed by the measurement and Fourier analysis of the ME response signal. It is shown that the ME voltage coefficient α_E generally decreases as the frequency increases from 1 kHz to 1 MHz except (i) at some discrete frequencies where the coefficient increases by an order of magnitude due to electromechanical resonance in the structure and (ii) a local maximum at 2-4 kHz in α_E vs. frequency due to relaxation processes caused by the conductivity of individual layers.     

Nonlinear magnetoelectric response of a bulk magnetostrictive-piezoelectric composite

Magnetoelectric effect in a bulk composite of nickel ferrite and lead zirconate titanate has been investigated by applying an ac magnetic field with no bias field. The measurements were carried out in the low-frequency region for harmonic magnetic field modulation with amplitude up to 3 kOe. The electric field induced by out-of-plane magnetic field exceeds that induced by in-plane magnetic field by approximately 4 times. Nonlinearity of ferrite magnetostriction of the sample results in a doubling in the frequency and a strong distortion of the ME signals. The magnetically induced voltage can be found by integrating the ordinary ME voltage coefficient over magnetic field.     

Pyroelectric effects in magnetoelectric multilayer composites

Magnetoelectric and pyroelectric properties have been investigated in heterostructures of nickel zinc ferrite (NZFO)-lead zirconate titanate (PZT) and lanthanum calcium manganite (LCMO)-PZT. The magnetoelectric (ME) coupling, mediated by mechanical strain, is found to be two orders of magnitude stronger in NZFO-PZT than in LCMO-PZT. The pyroelectric effect is investigated by measuring the current through the sample as the temperature is varied at 0.1 K/s. For NZFO-PZT the pyroelectric coefficient is in the range 0.2-15 nC/cm² K, depending on the temperature. A much weaker current is observed in LCMO-PZT. A reversal in the current direction is detected when the thermal cycle is switched from heating to cooling. The pyroelectric coefficient is found to scale with the strength of ME interactions. A clear correlation between pyroelectric current and ME interactions is evident from the results.     

Structural and magnetoelectric properties of MFe<Subscript>2</Subscript>O<Subscript>4</Subscript>–PZT (M = Ni,Co) and La<Subscript>x</Subscript>(Ca,Sr)<Subscript>1-x</Subscript>MnO<Subscript>3</Subscript>–PZT multilayer composites

Thick-film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite, La_0.7Sr_0.3MnO₃ (LSMO), or La_0.7Ca_0.3MnO₃ (LCMO) and lead zirconate titanate (PZT). Structural, magnetic, and ferromagnetic resonance characterization shows evidence for defect-free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite–PZT than in manganite–PZT. The ME voltage coefficient _E at room temperature is the highest in NFO–PZT and the smallest for LCMO–PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. The magnitude of _E correlates well with magnetic permeability for the ferrites. PACS 75.80.+q; 75.70.Gg; 75.60.-d     

铌酸钾钠基无铅压电陶瓷纵振换能器*

高性能环境友好型无铅压电陶瓷及其应用是当前压电材料研究的热点之一,为了探究其在水声换能器领域的应用潜力,该文对铌酸钾钠基无铅压电陶瓷和锆钛酸铅压电陶瓷纵振式换能器进行了对比研究。依据仿真结果优化结构尺寸,制作了两种换能器样机并测试了其在空气中和水中的电声性能。测试结果表明,铌酸钾钠基无铅压电陶瓷换能器的谐振频率为35kHz,最大发送电压响应为 151dB,声源级可达 190dB,在 26kHz~67kHz 的频率范围内发送电压响应的起伏不超过±4.5dB,谐振频率处-3dB 的指向性开角约为 76°。该无铅压电陶瓷换能器具有和锆钛酸铅压电陶瓷换能器相当的发射性能,有望推动无铅压电材料在水声换能器领域的应用进程。     

Magnetoacoustic resonance in ferrite-ferroelectric nanopillars

This work is concerned with the nature of ferromagnetic resonance (FMR) under the influence of acoustic oscillations with the same frequency as FMR. Here we provide the theoretical model for ME coupling at FMR in the nanopillars of ferrite in a piezoelectric matrix. Our calculations show that magnification of ME coefficient is obtained at the magnetoacoustic resonance (MAR) region where FMR and acoustic oscillations at electromechanical resonance (EMR) overlap. The clamping effect of the substrate for nanopillars is considered in determining the ME voltage coefficient. In addition, nanostructures based on single crystal ferrites take on special significance as magnetic resonance line width of such materials may be narrow enough to enable the observation of effects connected with magnetoelastic interaction. As an example, ME coefficient is estimated for the nanopillars of yttrium iron garnet in lead zirconate titanate matrix. The phenomenon is of importance for the realization of multifunctional ME nanosensors/transducers operating at microwave frequencies.     

偏置电压对磁致伸缩/压电层合换能结构磁电性能影响

分析和测试了偏置电压调整时PZT5/Terfenol-D/PZT8层合换能结构磁电性能. 提出了一种磁致伸缩/压电层合磁电换能结构的一阶谐振频率控制方法. 通过改变压电驱动层的直流电压对磁电层合结构的预应变进行改变, 从而调整谐振频率. 分析偏置电压、 应变、 弹性模量、 谐振频率和谐振磁电电压系数之间关系. 分析表明: 在较小应变情况下, 控制电压几乎可以线性调节谐振频率, 而层合结构谐振磁电电压系数几乎与偏置电压无关. 实验研究验证: 理论与实验结果较好吻合. 在-170 V-+170 V的偏置电压时, 谐振频率可以几乎线性调整. 最大频率调整量达到1 kHz, 偏置电压对一阶纵振频率的控制率达到: 2.94 Hz/V. 在偏置磁场为0-225 Oe时, 谐振频率调整量与偏置磁场无关. 偏置磁场会改变谐振磁电电压系数, 在大于178 Oe静态磁场偏置时, 磁电电压系数最大, 达到1.65 V/Oe.     

Frequency dependence of magnetoelectric interactions in layered structures of ferromagnetic alloys and piezoelectric oxides

Magnetoelectric (ME) interactions in layered structures of magnetostrictive and piezoelectric phases are mediated by mechanical deformation. Here we discuss the frequency dependence of ME coupling in bilayers and trilayers of Permendur, a ferromagnetic alloy, and lead zirconate titanate. Data on ME voltage coefficient versus frequency profiles reveal a giant ME coupling at electromechanical resonance. The maximum voltage coefficient of 90 V/cmOe is three orders of magnitude higher than low-frequency values. The ME interactions for transverse fields are an order of magnitude stronger than for longitudinal fields. These results are in agreement with theory. The resonance ME effect, therefore, is a novel tool for enhancing the magnetic-to-electric field conversion efficiency in the composites. PACS 75.80.+q; 75.50.Gg; 75.60.-d; 77.65.-j; 77.65.Ly; 77.84.Dy     

Thin film piezoelectric response characterisation using atomic force microscopy with standard contact mode imaging

This article introduces a technique for observing and quantifying the piezoelectric response of thin films, using standard atomic force microscopes (AFMs). The technique has been developed and verified using strontium-doped lead zirconate titanate (PSZT) thin films, which are known for their high piezoelectric response. Quantification of the electro-mechanical voltage coefficient d(33) (pm/V) is made directly based on the applied peak-to-peak voltage and the corresponding peak-to-peak displacement in the obtained scan image. Under the proposed technique the AFM is configured in contact mode, where the silicon nitride tip is set to follow the film displacement at a single point. A known sinusoidal voltage is applied across the film and the displacement determined as a function of time, rather than the typical AFM measurement of displacement versus tip position. The resulting raster image contains several bands, which are directly related to the AFM scan frequency and the applied sinusoidal voltage and its frequency. Different combinations of the AFM scan frequency and the applied sinusoid frequency have been used to characterise the PSZT thin films, with estimated values of d(33) between 109 and 205 pm/V.