Effect of interface bonding on the phase-transformation-aided magnetoelectric effect in ferromagnetic/ferroelectric composites

Based on modified constitutive equations and finite element method, calculations have been performed to study the effect of interface bonding on the phase-transition-aided magnetoelectric (ME) response in a new kind of NiMnGa/lead–zirconate–titanate (PZT) multiferroic laminate composites. The results quantitatively show that the ME effect is remarkably dependent on both the interface layer characteristics and the interface layer thickness. Stiffer and thinner interface layers are apt to produce higher ME effect. Calculations are in good agreement with available experimental results. Furthermore, the theoretical approach was improved to consider the enhancement in the magnetostriction of martensites induced by pre-applied opposing stress. Predictions reveal that the usage of single crystal Fe₇Pd₃ as ferromagnetic phase to form magnetoelectric composite with PZT can produce a high ME up to ~1 V/cm Oe.     

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.     

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.     

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。     

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.     

Magnetoacoustic resonance in tangentially magnetized ferrite-piezoelectric bilayers

The magnetoelectric (ME) effect in ferrite-piezoelectric bilayers has been theoretically studied at coinciding frequencies of the electromechanical resonance in the electric subsystem and ferromagnetic resonance in tangentially magnetized ferrite. Giant values of the ME voltage coefficient (50–70 V/A at 5 GHz) are predicted for the YIG-PZT system. In contrast to the case of a normally magnetized plate, the magnetoacoustic resonance in a tangentially magnetized sample takes place at a lower value of the magnetic bias field and a smaller ferrite layer thickness. This effect can be used for the development of multifunctional ME nanosensors and transducers operating in the microwave range.     

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.     

Magnetoelectricity in polyurethane films loaded with different magnetic particles

Particulate polymer composites consisting of Terfenol-D/Polyurethane, Fe₃O₄/Polyurethane, Nickel/Polyurethane and particulate composite layers were prepared by using a simple solution cast method. Magnetoelectric (ME) effect is characterized by measuring the amplitude of the magnetoelectric current versus different input parameters that appear in the theoretical current expression. The results yield two conclusions: 1.Whatever the filler type (Terfenol-D, Fe₃O₄ or Nickel), the microcomposites show a magnetoelectric effect. 2. The magnetostrictive property of the material does not have a direct influence on the ME effect since ME sensitivity is dc field independent and the magnetoelectric coefficient α_p has close values in ac field for all types of polymer fillers.     

Room-Temperature Giant Magnetoelectric Effect From Coils Cored With MnZn Ferrite

We have built coils with MnZn ferrite cores that demonstrate an appreciable giant magnetoelectric effect (GME). Their maximum magnetoelectric (ME) output is as high as 87 V/Oe at tens of kilohertz, which is remarkable for devices without any power supply. Our experimental and theoretical analyses suggest that the GME of the coils originates from $LC$ resonances. Our results show a practical way to design ME devices such as passive high-frequency sensitive magnetic sensors. We have found as well that attention should be paid to $LC$ resonance when performing ME spectral measurements.      

The nonlinear resonance magnetoelectric effect in magnetostrictive-piezoelectric structures

We have studied a magnetoelectric (ME) effect that is nonlinear with respect to the alternating magnetic field. It is established that resonance excitation of an alternating electric field takes place in magnetostrictive-piezoelectric bilayer structures under the action of alternating magnetic field at a frequency that is half as small as the electromechanical resonance frequency. The nonlinear ME effect, in contrast to the linear one, does not depend on the constant (magnetizing) bias field and is quadratic with respect to the alternating magnetic field.     

Linear and nonlinear magnetoelectric effects in lead zirconate titanate–nickel ferrite bulk composites

Linear and nonlinear magnetoelectric (ME) effects in lead zirconate titanate (PZT)–nickel ferrite bulk composites have been experimentally studied. The maximum values of a ME response signal for the linear and nonlinear ME effects amounted to 260 mV/A and 34 kV/m, respectively. A relationship between the linear and nonlinear ME effects is established based on analysis of experimental data.

     

Frequency dependence of the magnetoelectric effect in ceramic composites based on lead zirconate titanate and nickel ferrite

The magnetoelectric (ME) effect in ferrite-piezoelectric ceramic composites based on a nickel ferrite spinel and lead zirconate titanate (PZT) has been theoretically and experimentally studied. Using the method of effective medium, an expression for the ME coefficient is obtained and its frequency dependence is analyzed. It is shown that, in the region of electromechanical resonance, the magnitude of the ME effect exceeds that in a layered structure of the same components and is more than two orders of magnitude greater than the low-frequency value. The results of calculations for a nickel ferrite spinel-PZT composite are in good agreement with the experimental data.     

Theory of magnetoelectric effect in ferrite-piezoelectric hybrid composites

A theory of the magnetoelectric (ME) effect in a multilayer ferrite-piezoelectric hybrid composite is presented. Proceeding from the material equations and the equations of motion, an expression for the frequency dependence of the ME voltage coefficient is obtained which involves the parameters of the ferrite and piezoelectric phases. In the region of the electromechanical resonance of the composite, the ME voltage coefficient exhibits a sharp increase. The results of calculations for a Terfenol-D-PZT hybrid composite are in satisfactory agreement with experimental data.     

Influence of mechanical failure on the magnetoelectric response of magnetostrictive/piezoelectric multiferroic composite

Based on modified multi-field coupling equations, the magnetoelectric (ME) response of a new kind of Ni_47.4Mn_32.1Ga_20.5/PZT multiferroic composites are calculated by considering the mechanical failure of the brittle PZT substance. It is theoretically revealed that the Ni_47.4Mn_32.1Ga_20.5/PZT bilayer composites could produce an ideal giant ME (GME) response up to 120 V/cm Oe, much larger than the best reports up to now. However, the real ME response will be strongly limited by the mechanical strength of the brittle PZT. Reducing the PZT layer and using a mechanically stronger PZT material have been suggested to enhance the ME response.     

Magnetostriction via Magnetoelectricity: Using Magnetoelectric Response to Determine the Magnetostriction Characteristics of Composite Multiferroics

Technical Physics Letters - We propose a new method for determining the magnetostriction characteristics of composite multiferroics by measuring the magnetoelectric (ME) response of the material...     

Enhanced magnetoelectric coupling in Pb(Zr0.52Ti0.48)O3 film-on-CoFe2O4 bulk ceramic composite with LaNiO3 bottom electrode

By chemically depositing a conductive LaNiO₃ (LNO) electrode layer onto dense CoFe₂O₄ (CFO) ceramics, the magnetoelectric (ME) response in Pb(Zr_0.52Ti_0.48)O₃ (PZT)/CFO film-on-substrate system was significantly enhanced. Structural, morphological, ferroelectric, and piezoelectric analysis was performed for the present PZT/LNO/CFO film-electrode-substrate composites, whereby improved electric-related output was demonstrated. It was further shown that the maximum ME coefficient α _E31 could reach up to 155 mV/cm Oe, which was about 2.6 times higher than that in PZT film-on-CFO ceramics without bottom electrode layer. Further enhancement of ME response could be expected by preparing high-quality electrode layer with optimal thickness and improved fabrication processing for such film-electrode-substrate composites.     

Post-curing effect on magnetoelectric performance of single PZT rod/continuous Terfenol-D fiber/epoxy 1-1-3 composites

A magnetoelectric (ME) composite consisting of a single PZT rod embedded in a matrix of continuous Terfenol-D fiber and epoxy medium has been fabricated and characterized. With an optimized aspect ratio of the composite rods, a large ME effect has been observed. The magnetostrictive effect of the continuous Terfenol-D fiber/epoxy medium can be enhanced by imposing an optimal pre-loading stress on the material and this pre-loading stress can be induced by suitable heat treatment. Experimental results show that the ME effect of the single PZT rod/continuous Terfenol-D fiber/epoxy composites can be enhanced significantly by a post-curing process. A thermal stress-mediated continuous fiber composite model has been used to explain the ME enhancement of the post-cured composites.     

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.     

Magnetoelectric behavior in in situ grown piezoelectric and piezomagnetic composite-phase system

A few model combinations of piezoelectric (PE), perovskite and piezomagnetic (PM), spinel phase has been chosen on BaO-TiO-FeO-CoO quinary oxides system for in situ preparation of magnetoelectric composite materials by solid-state route. The various phases, which appeared during in situ preparation in different model systems, have been characterized by X-ray diffraction (XRD). The magnetoelectric effect (ME) of such composites has been measured by dynamic method. The present paper deals with a qualitative comprehension of the ME property of such composites in relation to their proposed composition model.     

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。