High Magnetoelectric Voltage Coefficient Research Articles

Magneto-electric effects in coaxial nanofibers of hexagonal ferrites and ferroelectrics

We report on magneto-electric (ME) effects in core-shell nanofibers of hexagonal ferrites and ferroelectrics synthesized by electrospinning. The core-shell structure in annealed fibers of M, Y, and W-type hexagonal ferrites and PZT was confirmed by electron and scanning microwave microscopy. Fibers showed ferroelectric polarization and magnetization smaller than for bulk samples. The ME coupling strength was measured by magnetic field H induced polarization and ME voltage coefficient (MEVC). In SrM-PZT fibers the remnant polarization decreased by as much as 20% with the application of H. The highest MEVC was measured for magnetic field assembled films of SrM–PZT fibers.

Enhanced Energy Conversion Performance of a Magneto–Mechano–Electric Generator Using a Laminate Composite Made of Piezoelectric Polymer and Metallic Glass

AbstractMagneto–mechano–electric (MME) generators, which convert ubiquitous stray magnetic field into electricity, have attracted significant attention as a permanent power source for innumerable sensors. In this study, a MME generator based on magnetostrictive metallic substrate and piezoelectric polymer is reported. After the metallic glass sheets are stacked using adhesives, ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) is spin‐casted onto Metglas lamination. The fabricated MME generator harvests an output peak voltage of ≈12.5 V under the applied alternating current magnetic field of 7 Oe at 38.2 Hz. A high magnetoelectric voltage coefficient of 910.14 V cm−1 Oe−1 obtained from the energy device is higher than those reported earlier in inorganic and polymeric piezoelectric components‐based MME generators. Moreover, finite element analysis using the multiphysics simulation is carried out to theoretically investigate the magnetoelectric energy harvesting of the fabricated MME generator. This research results achieve low cost, mechanical stability, eco‐friendliness, and high performance for MME generators, which is anticipated to provide a future direction for magnetoelectric energy harvesting.

Dielectric and magnetoelectric properties of (BiBa)(FeTiZn) O3/CoFe2O4 lead-free particulate composites

The magnetic, dielectric, and magnetoelectric (ME) properties of particulate composites containing lead-free piezoelectric 0.97[0.67BiFeO3-0.33BaTiO3]-0.03Bi(Zn0.5Ti0.5) O3 (BF33BT-3BZT) and magnetostrictive CoFe2O4 (CFO); (100-x)[BF33BT-3BZT]-xCFO, x = 13, 25, 37, 47 mol%; have been investigated. The pure ferroelectric BF33BT-3BZT shows a non-dispersive and sharp phase transition, while the composites exhibit relaxor behavior which is described by Vogel - Fulcher law. The ME voltage coefficient is studied as a complex quantity and its dependence on magnetic field is discussed within the framework of dynamic magnetostriction. The composite with x = 37 shows the highest ME voltage coefficient of 5.7 mV/cm.Oe. The results show that, compared to cobalt ferrite, the composite of BF33BT-3BZT with nickel ferrite produces larger ME voltage at a lower magnetic field, confirming that the magnetic field dependence of magnetostriction has a crucial role on the ME properties of the studied multiferroic composites.

Correlation of Interface Impurities and Chemical Gradients with High Magnetoelectric Coupling Strength in Multiferroic BiFeO3-BaTiO3 Superlattices.

The detailed understanding of magnetoelectric (ME) coupling in multiferroic oxide heterostructures is still a challenge. In particular, very little is known to date concerning the impact of the chemical interface structure and unwanted impurities that may be buried within short-period multiferroic BiFeO3-BaTiO3 superlattices during growth. Here, we demonstrate how trace impurities and elemental concentration gradients contribute to high ME voltage coefficients in thin-film superlattices, which are built from 15 double layers of BiFeO3-BaTiO3. Surprisingly, the highest ME voltage coefficient of 55 V cm-1 Oe-1 at 300 K was measured for a superlattice with a few atomic percent of Ba and Ti that diffused into the nominally 5 nm thin BiFeO3 layers, according to analytical transmission electron microscopy. In addition, highly sensitive enhancements of the cation signals were observed in depth profiles by secondary ion mass spectrometry at the interfaces of BaTiO3 and BiFeO3. As these interface features correlate with the ME performance of the samples, they point to the importance of charge effects at the interfaces, that is, to a possible charge mediation of ME coupling in oxide superlattices. The challenge is to provide cleaner materials and processes, as well as a well-defined control of the chemical interface structure, to push forward the application of oxide superlattices in multiferroic ME devices.

Induced ferromagnetism and magnetoelectric coupling in ion-beam synthesized BiFeO3–CoFe2O4 nanocomposite thin films

Ferrimagnetic CoFe2O4 (cobalt ferrite) is formed within an epitaxial BiFeO3 (bismuth ferrite) thin film matrix by Co channeled ion implantation and subsequent annealing. The presence of nanoscale CoFe2O4 crystals in the matrix is confirmed by x-ray diffraction using synchrotron radiation. The significantly increased magnetic moment and the low-temperature coercive field of the composite system evidence the formation of ferrimagnetic cobalt ferrite and its nanoscale character, respectively. The results demonstrate that ion beam synthesis is an appropriate method to controllably transform a planar system into a granular one, increasing the interface area between cobalt ferrite and bismuth ferrite. The ferroelectric nature of the BiFeO3–CoFe2O4 composite is confirmed by several scanning probe microscopy techniques. At room temperature, the composite exhibits a magnetoelectric voltage coefficient of αME = 17.5 V (cm · Oe)−1, while a single-phase BiFeO3 thin film shows a αME value of 4.2 V (cm · Oe)−1. The high magnetoelectric voltage coefficient is interpreted to be the result of the interfacial interaction between the ferrimagnetic CoFe2O4 nanocrystallites and the multiferroic BiFeO3 matrix.

Epitaxial Coherence at Interfaces as Origin of High Magnetoelectric Coupling in Multiferroic BaTiO3–BiFeO3 Superlattices

Multiferroic superlattices consisting of 15 double layers BaTiO3–BiFeO3 show a very high magnetoelectric voltage coefficient αME of up to 49 V cm−1 Oe−1 at 300 K, measured at 1 kHz with zero direct current (DC) bias magnetic field. However, the microscopic origins of such high αME values, and the temperature and DC magnetic field dependencies of αME are not understood up to now. Therefore, in this study two superlattices grown at high/low oxygen partial pressures having high/low αME values, respectively, are compared. While at high growth pressure the strain contrast in high‐resolution transmission electron microscopy images is limited to few layers at the substrate interface, the low‐pressure sample shows much more pronounced microstrain. This is additionally visualized in Fourier transformed images, and the out‐of‐plane lattice parameter of the single BaTiO3 layer is increased near the interface. In addition to a low density of oxygen vacancies, it seems to be important to avoid micromechanical clamping of the 2D single‐phase nanolayers of the multiferroic BaTiO3–BiFeO3 superlattices to achieve high magnetoelectric coupling.

The giant magnetoelectric effect in Fe73.5Cu1Nb3Si13.5B9/PZT thick film composites

The Fe73.5Cu1Nb3Si13.5B9/PZT thick film composites with excellent magnetoelectric (ME) coupling effect were synthesized by electrostatic spray depositing. The ME coupling characteristics of Fe73.5Cu1Nb3Si13.5B9/PZT thick film composites were investigated. It is found that the appropriate thickness ratio between magnetostrictive layers and piezoelectric layers (tm/tp) will be favorable to raise the resonance ME field output performance. The resonance frequency of ME field coefficient can be tuned by controlling tm/tp. The optimum resonance ME field coefficient of Fe73.5Cu1Nb3Si13.5B9/PZT thick film composites achieves 259.2 V/cm Oe at mechanical resonance frequency at 11.5 kHz with the dc bias magnetic field is 60 Oe. Remarkably, the proposed composites exhibit a giant ME effect and a higher ME voltage coefficient than the previous Terfenol-D/PZT laminated composites. It indicates that the mentioned Fe73.5Cu1Nb3Si13.5B9/PZT thick film composites have great potential for the application of highly sensitive magnetic field sensing and vibration energy harvesting.

Improved magnetoelectric performance of the Ni-P/Ni/Pb(Zr,TiO)3 cylindrical layered composites

The Ni-P/Ni/Pb(Zr,TiO)3 (PZT) cylindrical layered magnetoelectric (ME) composites have been prepared by electroless deposition and electrodeposition. The ME effect in the axial mode was researched in this paper. Compared with that of the Ni/PZT and Ni-P/PZT composites, the Ni-P/Ni/PZT composites have both lower optimal magnetic field and higher ME voltage coefficient. The reason for the ME improvement can be ascribed to the flux concentration effect and the compressive stress in the Ni layers induced by the high permeability Ni-P layers. These results open up a suitable way to enhance the sensitivity and optimize the design of ME devices for practical application.

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.

Enhanced magnetoelectric effects in composite of piezoelectric ceramics, rare-earth iron alloys, and shape-optimized nanocrystalline alloys

An enhancement for magnetoelectric (ME) effects is studied in a three-phase ME architecture consisting of two magnetostrictive Terfenol-D (Tb(0.3)Dy(0.7)Fe(1.92)) plates, a piezoelectric PZT (Pb(Zr,Ti)O3) plate, and a pair of shape-optimized FeCuNbSiB nanocrystalline alloys. By modifying the conventional shape of the magnetic flux concentrator, the shape-optimized flux concentrator has an improved effective permeability (μ(eff)) due to the shape-induced demagnetizing effect at its end surface. The flux concentrator concentrates and amplifies the external magnetic flux into Terfenol-D plate by means of changing its internal flux concentrating manner. Consequently, more flux lines can be uniformly concentrated into Terfenol-D plates. The effective piezomagnetic coefficients (d(33m)) of Terfenol-D plate and the ME voltage coefficients (α(ME)) can be further improved under a lower magnetic bias field. The dynamic magneto-elastic properties and the effective magnetic induction of Terfenol-D are taken into account to derive the enhanced effective ME voltage coefficients (α(ME,eff)), the consistency of experimental results and theoretical analyses verifies this enhancement. The experimental results demonstrate that the maximum d(33m) in our proposed architecture achieves 22.48 nm/A under a bias of 114 Oe. The maximum α(ME) in the bias magnetic range 0-900 Oe reaches 84.73 mV/Oe under the low frequency of 1 kHz, and 2.996 V/Oe under the resonance frequency of 102.3 kHz, respectively. It exhibits a 1.43 times larger piezomagnetic coefficient and a 1.87 times higher ME voltage coefficient under a smaller magnetic bias of 82 Oe than those of a conventional Terfenol-D/PZT/Terfenol-D composite. These shape-induced magnetoelectric behaviors provide the possibility of using this ME architecture in ultra-sensitive magnetic sensors.

Magnetoelectric effects in multilayered magnetostrictive/piezoelectric composites with Fe-based nanocrystalline alloy at zero bias magnetic field

This paper presents a comparison of the resonant magnetoelectric (ME) voltage coefficients for multilayered PZT/FeNi-FACE composites with Fe-based nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy (FeCuNbSiB) and without FeCuNbSiB. As the magnetic interaction between FeNi-FACE and FeCuNbSiB produces an internal magnetic field (Hint), it leads to the variation of the total dc magnetic bias and the ME voltage coefficient for multilayered PZT/FeNi-FACE composites with FeCuNbSiB, relative to multilayered PZT/FeNi-FACE composites without FeCuNbSiB. Correspondingly, a high ME voltage coefficient for multilayered PZT/FeNi-FACE composites with FeCuNbSiB at zero can be obtained. Furthermore, as the number of layer increases to 9, the zero-bias ME voltage coefficient first increases, and then decreases. The value of seven-layer composite reaches 5.14V/Oe, which is about 2.35 times higher than that for three-layer, 1.53 times higher than that for five-layer, and 1.22 times higher than that for nine-layer. Such high performances enable the ME composites to possess an ideal sensing and make them promising for self-bias ME sensor application.

Effect of CoFe2O4 mole percentage on multiferroic and magnetoelectric properties of Na0.5Bi0.5TiO3/CoFe2O4 particulate composites

Na0.5Bi0.5TiO3 (NBT), CoFe2O4 (CFO) as well as particulate composites containing different mole percentages of NBT and CFO were synthesized by the solid-state sintering route and characterized for their ferroelectric and ferrimagnetic hysteresis loops, magnetostriction and magnetoelectric (ME) output. The mole% of CFO was found to influence the ferroelectric and ferrimagnetic hysteresis loops as well as magnetostriction and piezomagnetic coefficients which in turn had a significant effect on the magnetoelectric voltage coefficient. The highest magnetoelectric voltage coefficient (α) of 0.5mV/cm/Oe was recorded in (65) NBT–(35) CFO composite.

A New Magnetoelectric Composite with Enhanced Magnetoelectric Coefficient and Lower Resonance Frequency

This study reports large magnetoelectric (ME) effect by attaching Ni and Metglas magnetostrictive layers to one free end of piezoelectric Pb(Zr,Ti)O3 (PZT) cantilever. By this structure, the influences of the bonding layer can be weakened so as to get relatively high ME voltage coefficient (αME) at resonance frequency. And the cantilever structural magnetostrictive material can supply stronger magnetic force to the PZT plate instead of the shear force in traditional structure, leading to an enhancement of αME at resonance frequency and generate a new resonance frequency of bending mode which is lower. Also, it can be used without bias field due to the built-in dc magnetic bias field between Ni and Metglas layers. Hence, it can obtain a larger αME at a lower resonance frequency at zero bias. The resonant αME at zero bias of the new composite reaches 50 V/cm∙Oe which is about 1.5~2 times as large as that of the traditional one. Besides, it greatly enhances the αME in a frequency range between two resonance frequencies. When we changed the length and thickness of Ni or Metglas layers, the results changed with them. Both the length and thickness have the optimum number to get a maximal αME. We also find if Ni and Metglas layers are not side to side aligned, αME at zero bias will decrease a lot.

Giant self-biased magnetoelectric response with obvious hysteresis in layered homogeneous composites of negative magnetostrictive material Samfenol and piezoelectric ceramics

Giant self-biased magnetoelectric (ME) response and obvious hysteresis are observed in trilayer homogenous ME laminate composite consisting of negative magnetostrictive Samfenol (SmFe2) plates and piezoelectric ceramic PZT (Pb(Zr,Ti)O3) plates. The large anisotropic field of SmFe2 oriented the direction [111] of easy magnetization results in an enhanced internal bias due to its huge intrinsic anisotropic constant. The experimental results demonstrate that this composite exhibits ∼30 times higher ME voltage coefficient than that of composite FeNi/PZT/FeNi with weak ME coupling at zero bias. These results provide the possibility of this homogeneous ME composite for ultra-sensitive magnetic field sensing without bias.

Observation of multiferroic properties and magnetoelectric effect in (x)CoFe2O4−(1−x)Pb0.7Ca0.3TiO3 composites

(x)CoFe2O4−(1 − x)Pb0.7Ca0.3TiO3 (CFO–PCT) magnetoelectric composites with x = 0.2, 0.4, 0.6 and 0.8 were synthesized using metallo-organic decomposition (MOD) chemical method. The structural, microstructural, dielectric, ferroelectric, magnetic and magnetoelectric properties of these composites were investigated. The structural and microstructural results indicate that CFO and PCT phases can coexist in the composite without any secondary phase. The dielectric constant and loss factor of the composites were studied as a function of frequency and temperature. The temperature dependent dielectric properties show two dielectric maxima one at below ∼385 °C and another at above ∼510 °C. The dielectric anomaly below 385 °C and that above 510 °C correspond to the transitions of ferroelectric and ferrite respectively of the magnetoelectric composites. The composites show both ferroelectric and ferromagnetic behaviors at room temperature with strong dependence on ferrite concentration. The magnetoelectric voltage coefficient increases linearly with increase in applied dc magnetic-bias field up to 8 kOe. The maximum value of the magnetoelectric (ME) voltage coefficient α ∼ 86 mV/cm Oe was measured for CFO–PCT composite having 80% ferrite content. The high ME voltage coefficient of CFO–PCT composites may be suitable for storage device applications.

Effect of Previous Milling of Precursors on Magnetoelectric Effect in Multiferroic $${\mathrm{Bi}_{5}\mathrm{Ti}_{3}\mathrm{FeO}_{15}}$$ Bi 5 Ti 3 FeO 15 Ceramic

$$\mathrm{Bi}_{5}\mathrm{Ti}_{3}\mathrm{FeO}_{15}$$ magnetoelectric (ME) ceramics have been synthesized and investigated. The ME effect can be described as an induced electric polarization under an external magnetic field or an induced magnetization under an external electric field. The materials in the ME effect are called ME materials, and they are considered to be a kind of new promising materials for sensors, processors, actuators, and memory systems. Multiferroics, the materials in which both ferromagnetism and ferroelectricity can coexist, are the prospective candidates which can potentially host the gigantic ME effect. $$\mathrm{Bi}_{5}\mathrm{Ti}_{3}\mathrm{FeO}_{15}$$ , an Aurivillius compound, was synthesized by sintering a mixture of $$\mathrm{Bi}_{2}\mathrm{O}_{3}, \mathrm{Fe}_{2}\mathrm{O}_{3}$$ , and $$\mathrm{TiO}_{2}$$ oxides. The precursor materials were prepared in a high-energy attritorial mill for (1, 5, and 10) h. The orthorhombic $$\mathrm{Bi}_{5}\mathrm{Ti}_{3}\mathrm{FeO}_{15}$$ ceramics were obtained by a solid-state reaction process at 1313 K. The ME voltage coefficient ( $$\alpha _\mathrm{ME}$$ ) was measured using the dynamic lock-in method. The highest ME voltage coefficient ( $$\alpha _\mathrm{ME} = 8.28\,\text{ mV }{\cdot }\text{ cm }^{-1}{\cdot }\text{ Oe }^{-1})$$ is obtained for the sample milled for 1 h at $$H_\mathrm{DC }= 4$$ Oe (1 Oe = 79.58 $$\text{ A }{\cdot }\text{ m }^{-1})$$ .

Strong magnetoelectric coupling in sol–gel derived multiferroic (Pb0.76Ca0.24)TiO3–CoFe2O4 composite films

A multilayer heterostructure composite thin films consisting of alternating layers (Pb0.76Ca0.24)TiO3 (PCT) and CoFe2O4 (CFO) were grown on Pt/Ti/SiO2/Si(100) substrate by a sol–gel process. X-ray measurements indicated high quality of crystallization of both PCT and CFO layers. The magnetic and ferroelectric properties of the composite were investigated. Well-defined polarization vs. electric field (P–E) and magnetic hysteresis (M-H) loops were obtained. A strong magnetoelectric (ME) response was observed in the sample which was subjected to an alternating magnetic field, and a high ME voltage coefficient αE = 870 mV/Oe cm was obtained for the composite thin films when applied magnetic field parallel to the sample plane.

INFLUENCE OF INTERFACE AND POLARIZATION ON MAGNETOELECTRIC COUPLING IN Ni-LEAD ZIRCONIUM TITANATE-Ni TRILAYERS DERIVED BY ELECTROLESS DEPOSITION

Magnetoelectric (ME) coupling in layered structures of magnetostrictive and piezoelectric phases are mediated by mechanical deformation and depends strongly on the interface conditions. Ni -lead zirconium titanate- Ni trilayers with neither electrodes nor bonding layers have been derived by electroless deposition. The structure of the electroless deposited Ni layer was characterized by X-ray diffraction. The cross-section of the Ni/PZT layers was investigated using scanning electron microscopy. The value of ME voltage coefficient (αE,31) increases as the interface roughness increases. The maximum of αE,31 for the Ni/PZT/Ni trilayers polarized after electroless deposition is higher than that for the Ni/PZT/Ni trilayers polarized before electroless deposition. It is essential to optimize the interface and the polarization to obtain higher ME voltage coefficient.

High magnetoelectric tuning effect in a polymer-based magnetostrictive-piezoelectric laminate under resonance drive

A polymer-based magnetoelectric (ME) laminate was fabricated by sandwiching one layer of thickness-polarized, length-stretched polyvinylidene fluoride (PVDF) piezoelectric polymer between two layers of length-magnetized, epoxy-bonded Tb0.3Dy0.7Fe1.92 (Terfenol-D) pseudo-1–3 magnetostrictive particulate composite in the thickness direction, and its resonance ME effect was investigated, both experimentally and theoretically, as a function of magnetic bias field (HBias). The laminate showed a high ME voltage coefficient (αV) of 233 mV/Oe at the fundamental resonance frequency (fr) of 60.6 kHz under a relatively low HBias of 0.6 kOe. By controlling HBias in the range of 0.02–1.5 kOe, nonlinear tunabilities as high as 1382 and 8.6% were achieved for αV and fr, respectively, as a result of the reduced eddy-current losses and enhanced non-180° domain-wall motion-induced negative-ΔE effect in the Terfenol-D composite layers as well as the increased compliance contribution from the PVDF polymer layer to allow the motion of non-180° domain walls in the Terfenol-D composite layers. This improved resonance ME tuning effect, together with the durable and tailorable natures, makes the laminate great promise for developing into tunable ME devices.

Enhanced magnetoelectric properties of Terfenol-D disk/Pb(Zr,Ti)O3 ring multiferroic heterostructures with Pb(Zr,Ti)O3 piezoelectric ring poled radially

Terfenol-D disk/Pb(Zr,Ti)O3 (PZT) ring multiferroic heterostructures were prepared and the magnetoelectric properties were characterized, for which PZT piezoelectric ring was poled radially. When the outer/inner diameter ratio of PZT ring was 1.6 and the bias and alternative magnetic fields were perpendicular to the thickness direction, the highest magnetoelectric voltage coefficient (dV/dH) at 1kHz of 165mVOe−1 was obtained, which was much higher than that for the previously reported disk-ring heterostrucutres with the piezoelectric phase poled along the thickness direction (75mVOe−1). The enhanced magnetoelectric properties of the present heterostructures were due to the larger component of the piezoelectric coefficient and the increased effective length of the piezoelectric phase that contributed to the magnetoelectric coupling.