Inverse magnetoelectric effect in ferrite-piezoelectric structures

A theory of the inverse magnetoelectric (ME) effect in bulk ferrite-piezoelectric composite materials is presented. Using the material equations and equations of motion, expressions for the frequency dependence of the inverse ME conversion coefficient and the voltage ratio in an ME transformer are obtained. These dependences exhibit a resonant character, with the ME response magnitude peaking at the resonance frequency. The ME transformer coefficient not only depends on the ME voltage coefficient and the number of turns in the induction coil, but is also influenced by the mutual orientation of the electric and magnetic fields and the sample geometry.     

Longitudinal and transverse magnetoelectric voltage coefficients of magnetostrictive/piezoelectric laminate composite: theory

This paper presents a novel, long-type of magnetostrictive and piezoelectric laminate composite design in which the layers are, respectively, magnetized/poled along their length axes, and a theory for modeling its behavior. Using piezoelectric and magnetostrictive constitutive equations, and an equation of motion, a magneto-elasto-electric bieffect equivalent circuit is developed. The circuit is used to predict the longitudinal and transverse magnetoelectric (ME) voltage coefficients of our Terfenol-D/Pb(Zr/sub 1-x/Ti/sub x/)O/sub 3/ laminate design. It is found that the longitudinal ME voltage coefficient is significantly higher (/spl sim/5x) than the transverse one, and that our new laminate design has significantly higher ME voltage coefficients under small applied direct current (DC) magnetic bias fields than designs reported previously by other groups. Experimental values were found to be coincidental with predicted ones.     

Giant magneto-electric effect in laminate composites

It has been discovered that laminate composites of longitudinally magnetized magnetostrictive and transversely poled piezoelectric layers (a L-T laminate composite) have a giant magneto-electric (ME) effect under a low magnetic bias. The ME voltage coefficient is over 110 mV/Oe at a magnetic bias H=500 Oe. This value is 5-10 times higher than that previously reported for transverse magnetized/transverse polarized (T-T) laminates of the same layer compositions at the same bias. In this paper, we also report the magneto-elasto-electric bieffect equivalent circuit of the L-T laminate composite and the corresponding theoretical formula of the magneto-electric voltage coefficient.     

Magnetoelectric coupling, efficiency, and voltage gain effect in piezoelectric-piezomagnetic laminate composites

The magnetoelectric (ME) effect of piezoelectric-magnetostrictive laminate composites, which is a product tensor, has been studied. Based on piezoelectric and piezomagnetic constituent equations, the longitudinal-mode vibration and equivalent circuits have been derived. The effective magnetoelectric coupling coefficient, voltage-gain, and output efficiency have been determined. Our results show: (i) that there is an extreme high voltage gain effect of >260 under resonance drive: the induced ME voltage is much higher than the input voltage to the coils for magnetic excitation; (ii) that there is an optimum ratio of the piezoelectric to piezomagnetic layer thicknesses, which results in maximum effective magnetoelectric coupling; and (iii) that the maximum output efficiency of magnetoelectric laminate at resonance drive is ∼98%, if eddy currents are neglected. This high ME voltage gain effect offers potential for power transformer applications.     

Magnetoelectric performance of cylindrical Ni–lead zirconate titanate–Ni laminated composite synthesized by electroless deposition

The cylindrical Ni–lead zirconate titanate (PZT)–Ni laminated composites with various magnetostrictive–piezoelectric phase thickness ratios were synthesized by electroless deposition. The influences of the bias magnetic field (H _dc) and the ac magnetic field frequency (f) on magnetoelectric (ME) effect are discussed. It is seen that the ME voltage coefficient depends strongly on H _dc and f. The ME voltage coefficient and electromechanical resonance frequency increase as the magnetostrictive–piezoelectric phase thickness ratio increases. The calculated resonant frequency increases with the magnetostrictive–piezoelectric phase thickness ratio, which agrees well with the experimental results. The maximum ME voltage coefficient of the cylindrical Ni–PZT–Ni laminated composite is 3.256 V cm⁻¹ Oe⁻¹, which is much higher than that of the plate laminated composite with the same magnetostrictive–piezoelectric phase thickness ratio. Electroless deposition is an efficient method to prepare ME laminated composites with complex structures. Proper resonant frequency and stronger ME effect can be obtained by optimizing the structure.     

Differential-mode vibrational noise cancellation structure for Metglas/Pb(Zr,Ti)O₃ fiber magnetoelectric laminates

A differential structure which has the ability to reject external vibrational noise for Metglas/Pb(Zr,Ti)O(3) (PZT) fiber-based magnetoelectric (ME) heterostructures has been studied. This type of ME structure functions better than conventional sensors as a magnetic sensor when used in an environment in which vibrational isolation is impractical. Sensors fabricated with this differential mode structure can attenuate external vibrational noise by about 10 to 20 dB at different frequencies, while simultaneously having a doubled ME voltage coefficient. Interestingly, in addition to offering a means of mitigating vibrational noise, this ME structure offers the potential to be a hybrid sensor, separating magnetic and acoustical signals.     

层状复合材料磁电效应的数值分析

压电与压磁(或磁致伸缩)层合板具有大的乘积效应磁电效应。本文采用有限元分析方法对压电/压磁层合板的磁电转换进行了计算,结果表明:外磁场方向对磁电转换效应有很大的影响,在层合板上下两面增加约束可以大大提高层合板的磁电转化效应;感生电压值随压磁/压电板厚比的增加而增加,而整个层合板的电场强度值在板厚比为1时达到最大。     

Effect of NiZnFeO4 content on PZT-pZN + NiZnFeO4 magnetoelectric composite

We fabricated and characterized the magnetoelectric (ME) properties of 3-0 ME composite materials comprised of the high piezoelectric voltage coefficient material, 0.9Pb(Zr0.52Ti0.48)O3-0.1 Pb(Zn1/3Nb2/3)O3 + 0.005Mn (PZT-PZN), and the magnetostrictive material, Ni0.8Zn0.2Fe2O4 (NZF). As the ME effect is generated by the product coupling between the piezoelectric properties and the magnetostrictive properties, the NZF content should be optimized for a higher ME coefficient. The dielectric constant and spontaneous polarization (P) were decreased with increasing NZF content before the percolation of the NZF particulates. However, as the NZF content exceeded the percolation content, the dielectric loss was dramatically increased due to the low resistivity of NZF. While the piezoelectric constant was decreased with increasing NZF content, the maximum magnetization was linearly increased. When we combined the piezoelectric and magnetostrictive effects, the ME composite sintered at 1200 degrees C with 20% NZF showed a maximum dE/dH of 27 mV/cm x Oe at a magnetic bias of 1240 Oe.     

Theory of magnetoelectric effect in ferromagnetic-piezoelectric bilayer structures

A theory of the magnetoelectric (ME) effect in a ferromagnetic-piezoelectric bilayer structure is presented. An expression for the ME voltage coefficient in terms of the parameters of the ferromagnetic and piezoelectric phases is obtained, and the dependence of this coefficient on the frequency and the ratio of the ferromagnetic and piezoelectric layer thicknesses is analyzed. The results of numerical calculations of the ME voltage coefficient for a permendur-PZT bilayer system are in satisfactory agreement with experimental data.     

Enhanced magnetoelectric effect in multiferroic composite beams due to flexoelectricity and transverse deformations

This paper is concerned with the exploration of the role of transverse normal and shear deformations on enhancing the magnetoelectric (ME) coefficient of multiferroic bilayer composite beams composed of a piezoelectric layer and a piezomagnetic layer. Analytical models have been derived based on the displacement field which accounts for both the transverse normal and shear deformations, Timoshenko beam theory and Euler Bernoulli beam theory. The induced flexoelectricity in the piezoelectric layer due to axial strain gradient and transverse shear strain gradient has also been taken into consideration for estimating the ME coefficient. It has been found that the contribution of transverse normal strain in the piezoelectric layer for enhancing the ME coefficient is significantly larger than that due to axial strain, transverse shear strain and flexoelectricity. For the particular values of the thicknesses of the piezoelectric layer and the piezomagnetic layer, the ME coefficient remains invariant for both thick and thin multiferroic composite beams.     

用于磁传感器的新结构磁电复合材料

研究了可用于磁场传感器的磁电复合材料, 对传统的磁电复合材料进行了结构创新, 采用条状PZT和 Terfenol-D 的材料体系, 用热固树脂进行粘合, Terfenol-D 沿长度方向磁化且PZT条沿厚度方向极化。与传统的1-3型复合不同的是: 每根PZT的输出极被串联起来。在同样的磁场激励下, 新型复合材料的输出电压为相同体积的同种结构复合材料的2.2倍, 增强了材料对磁场的灵敏度和抗噪声性能。      

Magnetoelectric Performances in Composite of Piezoelectric Ceramic and Ferromagnetic Constant-Elasticity Alloy

A high-quality factor magnetoelectric (ME) laminated composite employing a type of ferromagnetic constant-elasticity alloy (FCEA) and piezoelectric Pb(Zr,Ti)O₃ material is developed. The laminate is designed to operate as a half-wavelength (lambda/2), longitudinal resonator. The FCEA features high effective quality factor and low magnetomechanical coupling coefficient. This induces a particular ME characteristic. The theoretical analysis shows that the ME voltage coefficient (MEVC) at low frequency is directly proportional to the product of the electromechanical coupling factor in piezoelectric layer, magnetomechanical coupling factor, and the square root of magnetic permeability in FCEA layers. The MEVC at resonance and the ME sensitivity (under resonant drive) to dc bias magnetic field (H _dc) are dramatically increased by the effective quality factor (Qm) of the resonator. The measured vibrational characteristics reveal that the strain coefficient at resonance achieves 314.74 nm/A and Qm is ~ 1600. The MEVC at resonance (alphar) achieves 30.55 V/Oe (381.875 V/cm Oe), which is 1608 times higher than that at low frequency. In addition, alphar strongly depends on H _dc due to the high Qm, e.g., partalphar/partH _dc achieves 0.84 V/Oe². The ME resonator is potential for highly sensitive dc or quasi-static magnetic field sensing.     

Magnetoelectric properties of Ni/PZT/Ni layered composite for low field applications

A composite material when placed under the external magnetic/electric fields exhibits voltage/induced magnetization is known as magnetoelectric (ME) composite. Such composite materials should have ferroelectric and ferro/ferri magnetic phases as constituents. The magnetoelectric output is exhibited as a product property. Magnetoelectric composites are being used for variety of applications including resonators, filters, phase shifters, optical isolators, actuators and magnetic field sensors. Metal/ferroelectric/metal magnetoelectric composite using Ni and PZT as constituent phases has been fabricated in 2-2 composite pattern to study its product property. The paper presents magnetoelectric studies of Ni/PZT/Ni composite using low dc magnetic field magnetoelectric set-up. Using this ME set-up ME output of Ni/PZT/Ni composite is studied as a function of dc magnetic field. The results were analyzed to identify the useful magnetic field (dc and ac) range in which Ni/PZT/Ni sensor can be utilized for applications.     

Low-frequency magnetoelectric interactions in single crystal and polycrystalline bilayers of lanthanum strontium manganite and lead zirconate titanate

The magnetoelectric (ME) characterization of bilayers of lead zirconate titanate (PZT) and single crystal or hot-pressed polycrystalline lanthanum strontium manganite (LSMO) are discussed. Data on ME voltage coefficient have been obtained as a function of strength and orientation of bias magnetic field H, temperature, and frequency. The bilayers exhibit superior ME coupling compared to thick film multilayer composites and the strongest ME interactions are measured for samples with single crystal LSMO. Bilayers with single crystal LSMO show strong dependence of ME coefficient on H orientation and temperature, with a maximum value of 190 mV/cm Oe at 86 K. The frequency dependence of ME coefficient reveals a resonance enhancement due to radial acoustic modes. There is excellent agreement between theory and data for the H variation of ME coefficients.     

Analysis of Functionally Graded Magneto-Electro-Elastic Composites Using Hybrid/Mixed Finite Elements and Node-Wise Material Properties

A new class of hybrid/mixed finite elements, denoted "HMFEM-C", has been developed for modeling magneto-electro-elastic (MEE) materials. These elements are based on assuming independent strain-fields, electric and magnetic fields, and collocating them with the strain-fields, electric and magnetic fields derived from the primal variables (mechanical displacements, electric and magnetic potentials) at some cleverly chosen points inside each element. The newly developed elements show significantly higher accuracy than the primal elements for the electric, magnetic as well as the mechanical variables. HMFEM-C is invariant through the use of the element-fixed local orthogonal base vectors, and is stable since it is not derived from a multi-field variational principle; hence it completely avoids LBB conditions that govern the stability of hybrid/mixed elements. In this paper, node-wise material properties are used in order to better simulate the spatial material grading of the functionally graded materials (FGM). A computer code was developed, validated and used to calculate the three magnetoelectric (ME) voltage coefficients for piezoelectric-piezomagnetic (PE-PM) composites, namely, the out-of-plane, transverse and in-plane ME voltage coefficients. The effects of the piezoelectric phase volume fraction as well as the mechanical boundary conditions and loadings on the ME voltage coefficients are investigated. Also, the effects of grading functions in PE-PM composites with functionally graded layers, as well as single-layered functionally graded magneto-electro-elastic materials, on the three ME voltage coefficients are presented.     

A magnetic-field bending resonance sensor with maximum generated magnetoelectric voltage

A bending resonance magnetoelectric (ME) sensor with maximum generated response voltage is theoretically described. Based on the proposed model, the frequency dependence of the ME coefficient is determined. The optimum thickness of a piezoceramic layer is proposed, which provides a twofold increase in the response voltage. The phenomenon of antiresonance suppression of oscillations in the region of the third bending resonance at 95 Hz is discovered.     

AlN/FeCoSiB磁电复合薄膜的制备及其逆磁电效应研究

借助射频磁控溅射成功制备了AlN/FeCoSiB磁电复合薄膜, 探讨了退火条件对AlN薄膜压电性能和FeCoSiB薄膜磁性能的影响, 并研究了其逆磁电响应。结果显示, 500℃退火处理的AlN薄膜具有高度(002)择优取向和柱状生长结构; 经过300℃退火后FeCoSiB薄膜的磁场灵敏度提高。该磁电复合薄膜的逆磁电电压系数(α_CME)在偏置磁场(H_dc)为875 A/m时达到最大值62.5 A/(m·V); 且磁感应强度(B)随交变电压(V_ac)的变化呈现优异的线性响应(线性度达到1.3%)。这种AlN/FeCoSiB磁电复合薄膜在磁场或电场探测领域具有广阔的应用前景。     

Product properties of a two-phase magneto-electric composite: Synthesis and numerical modeling

Magneto-electric (ME) materials are of high interest for a variety of advanced applications like in data storage and sensor technology. Due to the low ME coupling in natural materials, composite structures become relevant which generate the effective ME coupling as a strain-mediated product property. In this framework, it seems to be possible to achieve effective ME coefficients that can be exploited technologically. The present contribution investigates the realization of particulate ME composites with a focus on their experimental and computational characterization. We will show that different states of pre-polarizations of the ferroelectric material have a decisive influence on the overall obtainable ME coefficient. Details on the synthesis of two-phase composite microstructures consisting of a barium titanate matrix and cobalt ferrite inclusions will be discussed. Subsequently we will employ computational homogenization in order to determine the effective properties of the experimental composite numerically. We investigate the influence of different states of pre-polarization on the resulting ME-coefficients. For the numerical incorporation of the pre-polarization we use a heuristic method.     

SMA混杂复合材料单层的被动阻尼

由形状记忆合金纤维、普通纤维、基体构成的混杂复合材料是一类用途广泛的智能材料结构系统。阻尼性能研究是结构被动振动控制的一项重要研究内容。本文采用混杂复合材料阻尼预测的细观力学理论计算SMA纤维混杂复合材料单层的阻尼特性。首先计算包含普通纤维和基体材料的复合材料介质的阻尼性能,其次计算由横观各向同性介质和SMA纤维构成的混杂材料的阻尼性能。通过计算实例分析SMA纤维混杂复合材料单层的正轴阻尼特性及其偏轴阻尼的特性随SMA纤维体积含量、纤维铺设角等参数改变的规律。     

Longitudinal and transverse magnetoelectric voltage coefficients of magnetostrictive/piezoelectric laminate composite: experiments

Magnetostrictive Terfenol-D (Tb(x)Dy(1-x)Fe2) and piezoelectric (Pb(Zr(1-x)Ti(x))O3) magnetoelectric (ME) laminate composites have been investigated experimentally for various modes of operation: longitudinal magnetized/longitudinal polarized (L-L mode), transverse magnetized/longitudinal polarized (T-L mode), and transverse magnetized/transverse polarized (T-T mode) ME modes. We report their experimentally determined performance characteristics based on our previously developed equivalent circuits for these various modes. Predicted and experimental results are in agreement that the L-L mode laminates have enhanced ME effects, and that, under low or zero magnetic bias, the L-L mode ME voltage coefficients are up to a factor of 5-20x higher than those of the T-L mode or T-T mode laminates. The maximum ME voltage coefficient of the L-L mode laminates is over 86 mV/Oe under a bias of 500 Oe.