Charge, voltage, and work-conversion formulas for magnetoelectric laminated composites

Strong self-biased magnetoelectric charge coupling in a homogenous laminate stack for magnetic sensor

Dielectric, magnetic and magnetoelectric studies on co-fired PbZr0.52Ti0.48O3–Co0.6Zn0.4Mn0.3Fe1.7O4 bilayer composite

The strain-mediated magnetoelectric (ME) coupling between piezoelectric (PE) and magnetostrictive (MS) components are established in various connectivities. Discovering new ME connectivity and elucidating the key factors governing the performance of ME composite are of critical importance to find advanced materials for modern electronics. Reported here is a novel ME coupling in 0-1 connectivity. The unique self-assembling ability of 1-dimension crystalline nanocellulose (CNC) nanowhiskers enables the establishment of ME coupling with 0-dimension cobalt ferrite (CFO) nanoparticles without the use of binder. The developed CFO/CNC 0-1 ME composites display a significant ME voltage coefficient (αME) as high as 0.135 mV cm-1 Oe-1. The CFO nanoparticles are also modified with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), to reduce their dispersion ability. A ME response related to the rearrangement of aggregated MS nanoparticles is observed in the CTAB-CFO/CNC composites, which differs from the typical magnetostriction induced ME effect in nanoparticulate ME composites.

Layer thickness and sequence effects on resonant magnetoelectric coupling in Ni/Pb(Zr,Ti)O3 cylindrical composites

We reported the high strength of magnetoelectric (ME) coupling of trilayeredcomposites prepared by electro-deposition. The ME coupling of Ni–leadzirconate titanate–Ni trilayered structure was measured in the range of1–120 kHz. The trilayered composites exhibit high ME voltage coefficient becauseof good interfacial bonding between piezoelectric and magnetostrictivelayers. The peak value of the ME voltage coefficient can be up to33 V cm−1 Oe−1 at the electromechanical resonance frequency. This magnetoelectric effect shows promise forapplication in transducers for magnetoelectric energy conversion.

Asymmetric and symmetric magnetoelectric (ME)-laminated composites with magnetostrictive layer FeNi and piezoelectric layer PZT are prepared. The longitudinal resonance ME voltage coefficient in the symmetric composite is approximately 1.57 times that in the asymmetric composite with same constituents due to the flexural deformation and asymmetric stress distribution in the asymmetric structure. By bonding an additional high-permeability FeSiB, combining FeSiB with FeNi forms magnetization-graded ferromagnetic materials. A stronger maximum ME voltage coefficient, a dual-peak phenomenon, and a self-bias ME effect are observed. The maximum ME voltage coefficients for asymmetric and symmetric composites reach 3.10 V/Oe and 5.67 V/Oe by adjusting the thickness of the FeCuNbSiB layer. The maximum zero-bias ME voltage coefficients for asymmetrical and symmetrical composite materials reach 2.19 V/Oe at 25 µm thickness of FeSiB and 2.87 V/Oe at 75 µm thickness of FeSiB. Such high performances enable the ME composites to possess ideal sensing and make them promising for self-bias current sensor applications.

Theoretical and experimental analysis of temperature dependent nonlinear behaviour of tri-layered magnetoelectric composites

Anisotropic magnetoelectric (ME) responses in bi-layered composites consisting of ferrites and polycrystalline/crystalline piezoelectrics were investigated by changing the applied DC magnetic field orientations, and origins for such effects were clarified by the competition between the dynamic piezomagnetic strain and the dynamic electro-mechanical strain from individual piezomagnetic/piezoelectric subsystems. Experimental results showed that maximum resonance ME voltage coefficient (MEVC) of 133.8.3 V/cm Oe under HDC = 23Oe can be obtained at θ = 0° for PMN-PT/NZFO laminate while one reached 115.3 V/cm Oe at higher field of 98Oe for θ = 75°. As rotation angle θ is varied from 0° to 360°, the HDC-orientation-dependent ME couplings were mainly determined by the dynamic piezomagnetic strain, and the dynamic piezoelectric coefficient versus θ profile can essentially track the MEVC versus θ profile. In addition, we found that the MEVC for PMN-PT/NZFO laminate is approximately twice as high as that of the PZT-8/NZFO laminate due to the stronger electro-mechanical strain of PMN-PT plates, Solid evidence was proved for the HDC-orientation-dependent ME coupling of the rectangle composite that is free of the influences of anisotropic crystalline orientation in PMN-PT plate. These findings open up a research pathway to move forward in this field and provide potential applications in vector angle sensors.

Resonance magnetoelectric couplings of piezoelectric ceramic and ferromagnetic constant-elasticity alloy composites with different layer structures

The giant magnetoelectric (ME) effect origining from the coupling of piezoelectricity and magnetic torque in flexible magnetoelectric torque (MET) unimorph devices has been investigated. The relation between the ME voltage coefficient and the thickness ratio of piezoelectric / elastic layers can be acquired from the experiments. Stainless steel, brass, and aluminum have been used as elastic layer for the devices. The experiment has verified the optimized thickness of elastic layers respectively. Experimental data indicates that the ME voltage coefficient at low frequency and at the resonance could be adjusted by changing the sample's elastic layers and thickness. This research has provided guides for engineers to constructed low cost and passive ME device with giant ME effect.

A low-frequency magnetoelectric (ME) response model of magnetostrictive/piezoelectric laminate composites based on multi-parameter analysis is presented. This model, taken the shear effect as the basis, analyzes the stress and strain of the magnetostrictive and piezoelectric layers by the stress function. The interlayer shear stress and the low-frequency ME response characteristics of ME laminate composites are obtained by using Hamilton principle of minimum energy and in consideration of the influence of stored magnetic field energy of magnetostrictive layer. The theoretical results show that the ME voltage coefficient is related with the magnetic permeability, Poisson ratio, magnetomechanical coupling coefficient, thickness ratio of magnetostrictive material and the Poisson ratio and electromechanical coupling coefficient of piezoelectric material. The influence of these parameters is analyzed. The experimental results show that analytical results are also compared to experimental test data with excellent correlation and their errors are less than 6%.

Resonance magnetoelectric (ME) responses are investigated for the ME laminate heterostructure consisting of positive magnetostrictive material FeCuNbSiB, negative magnetostrictive material Ni and piezoelectric material PZT-8. On one hand, both a built-in magnetic field induced by the strong magnetic interactions between positive magnetostrictive and negative magnetostrictive materials and an intrinsic anisotropic field with obvious hysteresis and remnant magnetization in Ni layer result in a large zero-biased ME effect. The corresponding zero-biased ME voltage coefficient reaches 10.12 V/Oe (126.5 V/cm Oe), which is about 3 times larger than that of traditional Ni/PZT-8 (NP) laminate. On the other hand, the additional stress produced by the high magnetic permeability FeCuNbSiB layer enhances the magnetostriction of Ni layer and ME response. The corresponding maximum ME voltage coefficient (dV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ME</sub> /dH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> ) is 12.09 V/Oe (150.87 V/cm Oe) at bias magnetic field H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> = 4 Oe. It is further found that even a step change of ac magnetic field less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> T can be clearly distinguished by the proposed ME composite. The value of ME voltage sensitivity to dc magnetic fields (dVME/dHdc) reaches ~76.7 mV/Oe at H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> = 5 Oe and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> = 0.1 Oe. Correspondingly, the proposed laminate heterostructure is able to possess both strong ac and dc magnetic field sensitivities.

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.

Since the piezoelectric/magnetostrictive laminate composite exhibits a strong magnetoelectric (ME) effect, it provides a novel method for detecting ac magnetic field. There are a number of researches on the development of ME composites and their applications in detecting magnetic fields. Dong et al. demonstrates the possibility of fabricating ac magnetic field sensors with high performances[1]. Especially, ME composite sensor can achieve the passive sensing of magnetic field and possesses high sensitivity, which greatly enhances the competitiveness of ME composite sensor against traditional magnetic sensors. ME voltage coefficient varies with H dc owing to the piezomagnetic coefficient's variation as a function of H dc , which shows a peak behavior near an optimum dc bias magnetic field H dc, opti . Hence, the ME composite sensor requires an external dc bias magnetic field to obtain the high ME sensitivity. However, the bias magnetic field is usually generated by using permanent magnets. It will increase the electromagnetic noise and increase the size of the sensor greatly, which is disadvantageous for the realization of high-sensitivity miniature magnetic sensors. Furthermore, the peak point is sharp and fixed, correspondingly small fluctuations of the optimum dc bias magnetic field will lead to a remarkable decrease of the ME voltage coefficient and degrade the ME composite performance significantly. In addressing these issues, the study of self-biased ME composite has provoked a great number of research activities and made progress [2-3]. However, these efforts have not obtained a wide range of dc bias response.

In this study, a magneto-mechano-electric (MME) composite cantilever made of a piezoelectric bimorph and magnets for low-frequency magnetoelectric (ME) coupling was analyzed theoretically and its MME coupling equivalent circuit was developed. Based on equivalent circuit analyses, the dependences of the ME performances, i.e., the ME voltage and charge coefficients, upon the material constants and geometrical parameters of the MME composite cantilever are numerically evaluated. The obtained ME equivalent circuit model provides a theoretical basis to understand and improve the performance of the MME composite cantilever for low-frequency ME coupling.