• Ceramist
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• v.23 no.1
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• pp.38-53
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• 2020

Magnetoelectric (ME) composites composed of magnetostrictive and piezoelectric materials derive interfacial coupling of magnetoelectric conversion between magnetic and electric properties, thus enabling to detect ultra-low magnetic field. To improve the performance of ME composite sensors, various research teams have explored adopting highly efficient magnetostrictive and piezoelectric phases, tailoring of device geometry/structure, and developing signal process technique. As a result, latest ME composites have achieved not only outstanding ME conversion coefficient but also sensing of ultra-low magnetic field below 1pT. This article reviews the recent research trend of ME composites for sensing of ultra-low magnetic field.

• Journal of Sensor Science and Technology
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• v.22 no.6
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• pp.379-386
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• 2013

The influences of the load resistance $R_L$ on the magnetoelectric (ME) characteristics of $NiZnFe_2O_4+PZT$ composite were investigated in the non-resonance frequency range. The ME coefficient peak increases with increasing $R_L$, but the frequency indicating the ME coefficient peak decreases with increasing $R_L$. The maximum output power peak is approximately $9.3{\times}10^{-10}mW/Oe$ near $R_L=3.3M{\Omega}$ at f=280 Hz, and the ME coefficient seems to be saturated at $R_L>20M{\Omega}$. This frequency shift effect of $R_L$ shows that the frequency range for an ME sensor application can be modulated with the appropriate value of $R_L$. The ME output voltage has a good linear response to the ac field Hac and shows fair stability over a range of temperatures. The measured non-linearity of this sample is approximately 0.8%. This sample will allow for a low-strength magnetic ac-field sensor. The result from this sample will serve as basic data for a signal-processing circuit system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.4
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• pp.229-241
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• 2021

Since 2010, polymer-based magnetoelectric (ME) composites have been developed with detailed investigations of multiferroic properties such as piezoelectric, magnetostrictive, and magnetoelectric, etc. In particular, as a piezoelectric polymer, poly(vinylidene fluoride) and its co-polymers have been widely used in ME composites for energy harvesting, health monitoring, environment treatment, and bio-medical applications. In this study, main research trend and selected experimental results of polymer-based ME composites are briefly reviewed with respect to composite structure as well as application field. A conclusion was drawn that the polymer-based ME composites would be feasible as flexible devices or functional membranes in the near future.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.45-50
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• 2020

Magnetoelectric (ME) composites were designed using the PMN-PZT single crystal and Ni foils; the properties and magnetic-field sensitivities of ME composites with different piezoelectric vibration modes (i.e., 31, 32, and 36 modes that depend on the crystal orientation of the single crystal) were compared. In the off-resonance condition, the ME coupling properties of the ME composites with the 32 and 36 piezoelectric vibration modes were better than those of the ME composites with the 31 piezoelectric vibration mode. However, in the resonance condition, the ME coupling properties of the ME composites were almost similar, irrespective of the piezoelectric vibration mode. Additionally, in the off-resonance condition (at 1 kHz), the magnetic-field sensitivity of the ME composites with the 36 piezoelectric vibration mode was up to 2 nT and those of the ME composites with the 31 and 32 piezoelectric vibration modes were up to 5 nT. These magnetic-field sensitivities are similar to those offered by conventional high-sensitivity magnetic-field sensors; the potential of the proposed sensor to replace costly and bulky high-sensitivity magnetic field sensors is significant.

• Journal of Magnetics
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• v.16 no.3
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• pp.271-275
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• 2011

This paper proposes a magnetoelectric (ME) composite transducer structure consisting of a magnetostrictive H-type Fe-Ni fork substrate and piezoelectric PZT plates. The fork composite structure has a higher ME voltage coefficient compared to other ME composite structures due to the higher quality (Q) factor. The ME sensitivity of the fork structure reaches 12 V/Oe (i.e., 150 V/cm Oe). The fork composite with two PZT plates electrically connected in series exhibits over 5 times higher ME voltage coefficient than the output of the rectangle structure in the same size. The experiment shows the composite of a Fe-Ni fork substrate and PZT plates has a significantly enhanced ME voltage coefficient and a higher ME sensitivity relative to the prior sandwiched composite laminates. By the use of a lock-in amplifier with 10 nV resolution, this transducer can detect a weak magnetic field of less than $10^{-12}$ T. This transducer can also be designed for a magnetoelectric energy harvester due to its passive high-efficiency ME energy conversion.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.611-614
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• 2018

Laminate composites composed of $0.95Pb(Zr_{0.52}Ti_{0.48})O_3-0.05Pb(Mn_{1/3}Sb_{2/3})O_3$ piezoelectric ceramic and Fe-Si-B based magnetostrictive amorphous alloy are fabricated, and the effect of control of the areal dimensions and the thickness of the piezoelectric layer on the magnetoelectric(ME) properties of the laminate composites is studied. As the aspect ratio of the piezoelectric layer and the magnetostrictive layer increases, the maximum value of the ME voltage coefficient(${\alpha}_{ME}$) increases and the intensity of the DC magnetic field at which the maximum ${\alpha}_{ME}$ value appears decreases. Moreover, as the thickness of the piezoelectric layer decreases, ${\alpha}_{ME}$ tends to increase. The ME composites exhibit ${\alpha}_{ME}$ values higher than $1Vcm^{-1}Oe^{-1}$ even at the non-resonance frequency of 1 kHz. This study shows that, apart from the inherent characteristics of the piezoelectric composition, small thicknesses and high aspect ratios of the piezoelectric layer are important dimensional determinants for achieving high ME performance of the piezoelectric-magnetostrictive laminate composite.

• Journal of Magnetics
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• v.20 no.4
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• pp.347-352
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• 2015

The magnetoelectric (ME) characteristics for Terfenol-D/PZT laminate composite dependence on bias magnetic field is investigated. At low frequency, ME response is determined by the piezomagnetic coefficient $d_{33,m}$ and the elastic compliance $s_{33}^H$ of magnetostrictive material, $d_{33,m}$ and $s_{33}^H$ for Terfenol-D are inherently nonlinear and dependent on $H_{dc}$, leading to the influence of $H_{dc}$ on low-frequency ME voltage coefficient. At resonance, the mechanical quality factor $Q_m$ dependences on $H_{dc}$ results in the differences between the low-frequency and resonant ME voltage coefficient with $H_{dc}$. In terms of ${\Delta}E$ effect, the resonant frequency shift is derived with respect to the bias magnetic field. Considering the nonlinear effect of magnetostrictive material and $Q_m$ dependence on $H_{dc}$c, it predicts the low-frequency and resonant ME voltage coefficients as a function of the dc bias magnetic field. A good agreement between the theoretical results and experimental data is obtained and it is found that ME characteristics dependence on $H_{dc}$ are mainly influenced by the nonlinear effect of magnetostrictive material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.333-341
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• 2022

Magnetoelectric (ME) composites are comprised of magnetostrictive and piezoelectric phases. Lots of theoretical and experimental works have been done on ME composites in the last couple of decades. The output performance of ME composites has been enhanced by optimizing the constituent phases, interface layer, dimensions of the ME composites, different operating modes, etc. However, the detailed information about the characterization of ME coupling in ME composites is not provided yet. Therefore, in this tutorial paper, we are giving an insight into the details of measurements of ME voltage coefficient of ME composites both at off-resonance and resonance conditions. A symmetric type Gelfenol/PMN-PZT/Gelfenol ME composites were fabricated by sandwiching (011) 32-mode PMN-PZT single crystal between two Galfenol plates by epoxy bonding are used for the example of ME coupling measurement. The details about the experimental setup used for the measurement of ME voltage coefficient are provided. Furthermore, a step-by-step measurement of ME voltage coefficient using computerized program is demonstrated. We believe the present experimental measurement details can help readers to understand the concept of ME coupling and its analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.515-521
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• 2013

Magnetoelectric(ME) bulk composites with PZT-PNN-PZN/$Fe_2O_4$ were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. ME devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time ${\tau}$ due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to $1+{\omega}^2{\tau}^2$ and the capacitance is in inverse proportion to $1+{\omega}^2{\tau}^2$ in the magnetic materials.

• Journal of Magnetics
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• v.16 no.2
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• pp.150-156
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• 2011

Magnetoelectric (ME) transducers were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. In this paper, a new broadband vibration energy harvester has been designed and fabricated to be efficiently applicable over a range of source frequencies, which consists of two cantilever beams, two magnetoelectric (ME) transducers and a magnetic circuit. The effects of the structure parameters, such as the non-linear magnetic forces of the ME transducers and the magnetic field distribution of the magnetic circuit, are analyzed for achieving the optimal vibration energy harvesting performances. A prototype is fabricated and tested, and the experimental results on the performances show that the harvester has bandwidths of 5.6 Hz, and a maximum power of 0.25 mW under an acceleration of 0.2 g (with g = $9.8\;ms^2$).