Magnetoelectric Performance Research Articles

Height-related magnetoelectric performance of PZT/Ni layered composites

The effect of height on performance of the PZT/Ni cylindrical bilayered magnetoelectric (ME) composites was studied in situ in this paper. Multiple resonant peaks appear between 1 and 300 kHz frequency for cylinders of different heights. The first resonance frequency does not change with the cylinder height decreasing, but the second and the third resonant frequencies increase. The first three resonant modes are attributed to the cylinder radial, first-order height resonance, and second-order height resonance, respectively. The appropriate size and resonance frequency were chosen to obtain the highest ME voltage coefficient when designing cylindrical bilayered magnetoelectric devices. This article provides reference to design cylindrical magnetoelectric devices.

Magnetoelectric effect in FeCo/PMN-PT/FeCo trilayers prepared by electroless deposition of FeCo on PMN-PT crystals with various orientations

The magnetoelectric (ME) effect was studied in the FeCo/PMN-PT/FeCo trilayer composites prepared by electroless deposition of the FeCo layers on the single crystal PMN-PT substrates with various crystal cuts. X-ray diffraction reveals that the orientation of PMN-PT substrate has no effect on the growth of FeCo layer. The structures with PMN-PT crystals of various orientations have different acoustic resonance frequencies. FeCo/PMN-PT/FeCo composites with PMN-PT of 〈001〉L×〈01‾1〉W×〈011〉T crystal cut shows superior ME performance, which is due to the highest piezoelectric module of PMN-PT.

(Invited) Fabrication and Dielectric Properties of BaTiO3 Thin Films on Polycrystalline Ni Foils

The BaTiO3 (BTO) thin films were deposited on polycrystalline Ni foils using a chemical solution approach. We show that the interface between the BTO film and the Ni foil plays a critical role in determining the dielectric and magnetoelectric (ME) properties of this flexible assembly. A pretreatment process of nickel foils with hydrogen peroxide (H2O2) solution has been conducted to form thin nickel oxide layers on the surfaces for the growth of BTO films. Both the concentration of H2O2 solution and the pretreated time were found to strongly affect the dielectric constant of BTO films, which is likely to be related to the evolution of nickel oxide at the interface during the growth of BTO films. The growth dynamics was systematically studied to optimize the single phase BTO films with good dielectric properties. Our results have demonstrated that not only a well-controlled interface between the BTO film and the Ni substrate can be achieved, but also an good dielectric and ME performance can be accomplished.

A magneto-mechano-electric coupling equivalent circuit of piezoelectric bimorph/magnets composite cantilever

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.

Large magnetoelectric coupling in Co4Nb2O9

Magnetoelectric materials which simultaneously exhibit electric polarization and magnetism have attracted more and more attention due to their novel physical properties and promising applications for next-generation devices. Exploring new materials with outstanding magnetoelectric performance, especially the manipulation of magnetization by electric field, is of great importance. Here, we demonstrate the cross-coupling between magnetic and electric orders in polycrystalline Co4Nb2O9, in which not only magnetic-field-induced electric polarization but also electric field control of magnetism is observed. These results reveal rich physical phenomenon and potential applications in this compound.

Electrospun barium titanate/cobalt ferrite composite fibers with improved magnetoelectric performance

In this study, we use a versatile sol–gel based electrospinning technique to fabricate nanostructured barium titanate (BaTiO3)/cobalt ferrite (CoFe2O4) composite fibers and analyze their magnetoelectric response.

Optimization of the Magnetoelectric Response of Poly(vinylidene fluoride)/Epoxy/Vitrovac Laminates

The effect of the bonding layer type and piezoelectric layer thickness on the magnetoelectric (ME) response of layered poly(vinylidene fluoride) (PVDF)/epoxy/Vitrovac composites is reported. Three distinct epoxy types were tested, commercially known as M-Bond, Devcon, and Stycast. The main differences among them are their different mechanical characteristics, in particular the value of the Young modulus, and the coupling with the polymer and Vitrovac (Fe39Ni39Mo4Si6B12) layers of the laminate. The laminated composites prepared with M-Bond epoxy exhibit the highest ME coupling. Experimental results also show that the ME response increases with increasing PVDF thickness, the highest ME response of 53 V·cm(-1)·Oe(-1) being obtained for a 110 μm thick PVDF/M-Bond epoxy/Vitrovac laminate. The behavior of the ME laminates with increasing temperatures up to 90 °C shows a decrease of more than 80% in the ME response of the laminate, explained by the deteriorated coupling between the different layers. A two-dimensional numerical model of the ME laminate composite based on the finite element method was used to evaluate the experimental results. A comparison between numerical and experimental data allows us to select the appropriate epoxy and to optimize the piezoelectric PVDF layer width to maximize the induced magnetoelectric voltage. The obtained results show the critical role of the bonding layer and piezoelectric layer thickness in the ME performance of laminate composites.

Analysis of the low-frequency magnetoelectric performance in three-phase laminate composites with Fe-based nanocrystalline ribbon

The theoretical analysis of magnetoelectric (ME) performance in three-phase Terfenol-D/PZT/FeCuNbSiB (MPF) laminate composite is presented in this paper. The ME couplings at low frequency for ideal and less than ideal interface couplings are studied, respectively, and our analysis predicts that (i) the ME voltage coefficient for ideal interface coupling increases with the increasing layers (n) of Fe-based nanocrystalline ribbon FeCuNbSiB (Fe73.5Cu1Nb3Si13.5B9) while the sizes of PZT (Pb(Zr1−xTix)O3) and Terfenol-D (Tb1−xDyxFe2−y) are kept constant, and then it tends to be a constant when the layers of FeCuNbSiB are >100; (ii) by introducing the interface coupling factor k and considering the degradation of d33m,f with n, the ME voltage coefficient for a less than ideal interface condition is predicted. As the FeCuNbSiB layer increases, it first increases and reaches to a maximum value, and then slowly decreases. Various MPF laminates are fabricated and tested. It is found that the theoretical predictions for the consideration of actual boundary conditions at the interface are in agreement with the experimental observations. This study plays a guiding role for the design of MPF composite in real applications.

Improving the Performance of High Temperature Piezopolymers for Magnetoelectric Applications

Piezoelectricity in amorphous polymers is mainly due to the orientation polarization of the molecular dipoles. Aromatic polyimides are high-performance polymeric materials possessing large molecular dipoles. We already reported good magnetoelectric performance of laminate composites with Vitrovac 4040®as magnetostrictive component and the 2,6(b-CN)APB/ODPA (poli 2,6) polyimide as the piezoelectric. Although the piezoelectric response of this polyimide is good, its mechanical properties can be improved. To combine the best mechanical and piezoelectric response in the same polymer, copolyimides have been synthesized by reaction of the 4,4-oxydiphtalic anhydride (ODPA) with a mixture of 1,3-Bis-2-cyano-3-(3-aminophenoxy) phenoxybenzene (diamine 2CN) and 1,3-Bis (3-aminophenoxy) benzene (diamine 0CN). We present the piezoelectric, mechanical and ME performance of laminate composites of these copolyimides.

Elastomechanical Study of Magnetoeletric Coupling in Bilayer of Lithium Zinc Ferrite and Lead Zirconate Titanate

A theoretical model based on the constitutive equations of piezoelectrics and magnetostrictor is introduced to discuss the magnetoelectric (ME) coupling in freebody bilayer containing magnetostrictive and piezoelectric phases. The ME coupling at low frequency of Ni0.8Zn0.2Fe2O4–PZT bilayer have been studied by using the model and the corresponding material parameters of individual phases. The results show that the ME voltage coefficients can increase to a maximum at a given volume fraction of piezoelectric phase. An approximately linear increase of the maximum has been obtained with strengthening interface coupling. Analysis shows that large magnetostriction, appropriate volume fraction and ideal interface coupling are key ingredients for obtaining excellent ME performance.

ChemInform Abstract: Magnetoelectric Interactions in Lead‐Based and Lead‐Free Composites

AbstractReview: 187 refs.

Fabrication of a plane-parallel interface in Ni/PbZr0.2Ti0.8O3 heterostructures

A process has been proposed for producing a plane-parallel ferromagnetic/ferroelectric interface, which ensures a reproducible magnetoelectric performance of Ni/PbZr0.2Ti0.8O3 (PZT) heterostructures. Its principle is to smooth the initial surface profile of the PZT ceramic substrate to a submicron level by sequential deposition/sputtering of three layers 0.2, 0.1, and 0.05 μm in thickness through ion beam sputtering of a target having the same composition as the substrate, followed by the growth of a nickel film on the smoothed surface. This allows one to preclude film bulging and spalling and ensures high quality of the interface.

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.

Effect of Permeability and Piezomagnetic Coefficient on Magnetostrictive/Piezoelectric Laminate Composite

The magnetostrictive material is magnetized in magnetic field and produces a nonuniform demagnetizing field inside and outside it. The demagnetization is decided by the permeability of magnetostrictive material and its size. The magnetoelectric performances are determined by the synthesis of the applied and demagnetizing fields. An analytical model is proposed to predict the magnetoelectric voltage coefficient (MEVC) of magnetostrictive/piezoelectric laminate composite using equivalent circuit method, in which the nonuniform demagnetizing field is taken into account. The theoretical and experimental results indicate that the MEVC is positively connected with the permeability and the piezomagnetic coefficient of magnetostrictive material. To obtain the maximum MEVC, both the permeability and the piezomagnetic coefficient of magnetostrictive material should be taken into account in selecting the suitable magnetostrictive material.

Magnetoelectric Interactions in Lead-Based and Lead-Free Composites.

Magnetoelectric (ME) composites that simultaneously exhibit ferroelectricity and ferromagnetism have recently gained significant attention as evident by the increasing number of publications. These research activities are direct results of the fact that multiferroic magnetoelectrics offer significant technological promise for multiple devices. Appropriate choice of phases with co-firing capability, magnetostriction and piezoelectric coefficient, such as Ni-PZT and NZFO-PZT, has resulted in fabrication of prototype components that promise transition. In this manuscript, we report the properties of Ni-PZT and NZFO-PZT composites in terms of ME voltage coefficients as a function of frequency and magnetic DC bias. In order to overcome the problem of toxicity of lead, we have conducted experiments with Pb-free piezoelectric compositions. Results are presented on the magnetoelectric performance of Ni-NKN, Ni-NBTBT and NZFO-NKN, NZFO-NBTBT systems illustrating their importance as an environmentally friendly alternative.

Enhanced magnetoelectric effect in a stress-biased lead magnesium niobate-lead titanate single crystal/Terfenol-D alloy magnetoelectric sensor

A stress-biased magnetoelectric sensor with a built-in permanent magnet has been fabricated using piezoelectric lead magnesium niobate-lead titanate single crystal and magnetostrictive Terfenol-D alloy. The resonance characteristics and magnetoelectric performance of the sensor have been evaluated under different stress-biased conditions. The resonance of the sensor shifts to higher frequency with increasing preloading stress. Due to the piezoelectric and magnetostrictive enhancements under preload, the device exhibits a giant magnetoelectric voltage coefficient of 0.22 V/Oe at a preloading stress of 2.5 MPa. This compact device has the potential to be used as a standalone sensor without requiring external power input.

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 (Hdc) and the ac magnetic field frequency (f) on magnetoelectric (ME) effect are discussed. It is seen that the ME voltage coefficient depends strongly on Hdc 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.

Bath temperature effect on magnetoelectric performance of Ni–lead zirconate titanate–Ni laminated composites synthesized by electroless deposition

Magnetoelectric (ME) Ni–lead zirconate titanate–Ni laminated composites have been prepared by electroless deposition at various bath temperatures. The structure of the Ni layers deposited at various bath temperatures was characterized by X-ray diffraction, and microstructures were investigated by transmission electron microscopy. The magnetostrictive coefficients were measured by means of a resistance strain gauge. The transverse ME voltage coefficient α E,31 was measured with the magnetic field applied parallel to the sample plane. The deposition rate of Ni increases with bath temperature. Ni layer with smaller grain size is obtained at higher bath temperature and shows higher piezomagnetic coefficient, promoting the ME effect of corresponding laminated composites. It is advantageous to increase the bath temperature, while trying to avoid the breaking of bath constituents.

Frequency response of magnetoelectric 1–3-type composites

A three-phase magnetoelectric (ME) composite consisting of Pb(Zr,Ti)O3 rods embedded in a matrix of Terfenol-D/epoxy (TDE) pseudo 1–3 composites has been fabricated. Besides the large ME effect, its frequency response under a magnetic bias field has been studied. It was found that the resonance shifts to lower frequency with increasing bias field. Due to the magnetomechanical characteristics of the TDE pseudo 1–3 medium, the composite shows a similar trend in ME performance. Magnetic-field dependence of the frequency shift provides a means to tune the performance of ME sensors based on the composite.

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

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A high-quality factor magnetoelectric (ME) laminated composite employing a type of ferromagnetic constant-elasticity alloy (FCEA) and piezoelectric Pb(Zr,Ti)O<formula formulatype="inline"><tex Notation="TeX">$_{3}$</tex></formula> material is developed. The laminate is designed to operate as a half-wavelength <formula formulatype="inline"><tex Notation="TeX">$(\lambda/2)$</tex></formula>, 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 <formula formulatype="inline"> <tex Notation="TeX">$(H_{\rm dc})$</tex></formula> are dramatically increased by the effective quality factor <formula formulatype="inline"><tex Notation="TeX">$(Q_{m})$</tex> </formula> of the resonator. The measured vibrational characteristics reveal that the strain coefficient at resonance achieves 314.74 nm/A and <formula formulatype="inline"><tex Notation="TeX">$Q_{m}$</tex></formula> is <formula formulatype="inline"><tex Notation="TeX">${\sim} 1600$</tex></formula>. The MEVC at resonance <formula formulatype="inline"><tex Notation="TeX">$(\alpha_{r})$</tex> </formula> achieves 30.55 V/Oe (381.875 V/cm Oe), which is 1608 times higher than that at low frequency. In addition, <formula formulatype="inline"><tex Notation="TeX">$\alpha_{r}$</tex></formula> strongly depends on <formula formulatype="inline"> <tex Notation="TeX">$H_{\rm dc}$</tex></formula> due to the high <formula formulatype="inline"><tex Notation="TeX">$Q_{m}$</tex></formula>, e.g., <formula formulatype="inline"><tex Notation="TeX">$\partial \alpha_{r}/\partial H_{\rm dc}$</tex></formula> achieves 0.84 V/Oe<formula formulatype="inline"><tex Notation="TeX">$^{2}$</tex></formula>. The ME resonator is potential for highly sensitive dc or quasi-static magnetic field sensing. </para>