Magnetoelectric Composites Research Articles

WITHDRAWN: Ferroelectric relaxor-PbTiO3 single crystal based magnetoelectric composites and devices

WITHDRAWN: Ferroelectric relaxor-PbTiO3 single crystal based magnetoelectric composites and devices

Magnetoelectric properties of CoFe2O4/BNT–BT0.08 biphasic nanocomposites, with 0–3 connectivity, prepared by sol-gel method

Motivated by the goal of developing ultralow power, smart and multifunctional nano (micro) electronic devices, research has shown unwavering interest in synthesis methods, architectures and interphase connectivity of composites containing magnetostrictive and piezoelectric phases, known as magnetoelectric (ME) materials. Herein we report on CoFe2O4/0.92Bi0.5Na0.5TiO3–0.08BaTiO3 biphasic ME composites, obtained by sol-gel chemistry, by mixing the precursor sols of the two phases into one precursor sol and further transforming it into gel, with the goal of obtaining homogeneous nanocomposites with magnetoelectric properties. The structural properties, the temperature dependance of dielectric properties, the magnetic and magnetoelectric properties of these biphasic mixtures, with various molar ratios CoFe2O4/BNT–BT0.08 = 0.5:1, 1:1 and 1.5:1, are investigated. It is observed that the amount of CoFe2O4 and the synthesis in situ of these composites influences their macroscopic properties showing a high difficulty of carrying out an efficient poling resulting in small piezoelectric and magnetoelectric response. It was concluded that the synthesis procedure, the type of architecture and the interphase connectivity are of outmost importance for magnetoelectric properties based on lead-free materials.

Cylindrical magnetoelectric FeGa/PZT composite for lightning current sensing applications

Magnetoelectric (ME) composites have been proven to apply to current sensors. However, the previously reported ME materials-based current sensors mainly focus on direct current and sine alternating current sensing, which put a critical limit on the measurement of transient current. In this paper, a cylindrical ME composite consisting of a magnetostrictive Fe83Ga17 (FeGa) cylinder and a piezoelectric Pb(Zr, Ti)O3 (PZT) circular tube is fabricated for lightning current sensing applications. The time-domain output voltage of the FeGa/PZT composite is simulated and measured in detail. Under the excitation of 8/20 µs lighting current, the output voltage of the composite can change with the current. But the damping oscillation at its resonant frequency is observed. Furthermore, to obtain an obvious ME response, the FeGa/PZT cylinder and current-carrying wire should be arranged closely and in an orthogonal way. When the amplitude of 8/20 µs lightning current is in the range of 500 A–9 kA, the ME FeGa/PZT composite shows a sensitivity of 1.36 mV A−1, a linear response (R 2 = 0.9993), and a small return error (0.12 V). These results provide that the ME composite is suitable to be used in non-contact lightning current measurements.

Application of Heat Treatment to Optimize the Magnetostrictive

The heat treatment effect of the magnetostrictive component in magnetoelectric (ME) composites consisting of a piezoelectric and magnetostrictive material has been studied. The dependence of the ME voltage coefficient on frequency was experimentally found without heat treatment and with annealing from 200 to 500°C of the AMAG493 amorphous alloy, which acted as a magnetostrictive component. It is shown that with an increase in the processing temperature of an amorphous alloy, an increase in the ME voltage coefficient is observed: the maximum value of the ME coefficient was observed at a temperature of 350°C and amounted to 29.52 V cm–1 Oe–1 at a resonance frequency of 54 kHz. It has been proven that the increase in the ME voltage coefficient occurs due to the improvement in the characteristics of the amorphous alloy during heat treatment, which leads to partial nanocrystallization of the material.

Enhanced near-field radiation of acoustic-actuated antennas using embedded magnetoelectric composites

Acoustic-actuated antennas operate at the acoustic wave resonance rather than electromagnetic (EM) wave resonance and thus show a significant superiority for the miniaturization of antennas. This paper designs a new acoustic-actuated antenna using embedded magnetoelectric (ME) composites, to improve the radiations of ME antennas through the enhanced strain transfer at the interfaces between different phases. The performance of the ME antenna is examined through a multiphysics finite element method with considering the nonlinear magnetostrictive model. Then, three optimum schemes are proposed for the improvement of the ME antenna, which are also verified by the simulation results. It has been demonstrated that the EM radiations of the embedded ME composite are effectively improved by changing its sizes or configuration. Due to the magnetic flux and stress concentration effects, the maximum |E| and |H| radiations are respectively enhanced by 88 % and 97 % via using a trapezoidal magnetostrictive layer. The effects of magnetic bias and pre-stress indicate that near-field radiations of the ME antennas with fixed dimensions can be enhanced by external multi-physics fields. This simulation may facilitate the understanding of nonlinear CME behavior as well as provide a basis for the design of tunable ME antennas.

Grain size and piezoelectric effect on magnetoelectric coupling in BFO/PZT perovskite-perovskite composites

Magnetoelectric multiferroics are provoking much research activity for their potential applications in novel multifunctional devices. Compared with single-phase multiferroics, magnetoelectric composites have competitive advantages. The magnetoelectric coupling of composites is heavily influenced by composition and grain size. We prepared BFO/PZT composites with separate phases via the solid-state sintering method. We show that equal molar ratio composition has a better magnetoelectric coupling response than other compositions. The composites with nano bismuth ferrite have better magnetoelectric coupling performance, and these with both nano grain sizes present the highest magnetoelectric voltage coefficients (αE = 16.9 mV cm−1 Oe−1). The strain-mediated mechanism was confirmed via a comparison between strain response and polarization of nano/micro type composites with the composition of 3:7. We found that the magnetoelectric voltage coefficient αE positively correlates with strain response instead of polarization in BFO/PZT composites, which provides experimental evidence for the strain-mediated ME composite theory.

Thermally stable multi-directional magnetoelectric based embedded magnetic sensor

Owing to the multifunctional behavior possessed by magnetoelectric (ME) composites, they are sought-after materials for various magnetic field sensing applications. This article proposes a three-directional ME-based embedded magnetic sensor that has been fabricated using the press-fit technique. The employed fabrication method negates the use of epoxy in the ME sensor, thus enabling its use at elevated temperatures in excess of 100 ∘C. The fabricated sensor is tested using an experimental setup capable of producing ac and dc bias magnetic fields in three coordinate directions. Experiments are performed for various dc magnetic field conditions, including x, y, z directions, their simultaneous combinations, and magnetic field aligned at an angle with the sensor. Under all testing conditions, the embedded sensor shows a significantly high output voltage response. Additionally, the effect of the magnetic field generated by the double magnet system and single magnet system on the sensor performance has also been demonstrated, wherein the embedded sensor is observed to be marginally affected by magnetic field due to the presence of only one magnet. Finally, quasi-static ME measurements are performed at elevated temperatures up to 100 ∘C, and it is observed that the novel embedded sensor has reliable sensing capabilities in aggravated thermal environments even in excess of 100 ∘C. Thus, the proposed three-directional embedded magnetic sensor offers reliable response under all conditions of magnetic field and temperature and can thus be a reliable alternative for the traditionally used layered-based counterparts.

A comparative study on rigid and flexible magnetoelectric composites: Review

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators.

Self-assembly hollow magnetoelectric composites emerging tunable property between microwave absorption and shielding with light-weight and broad bandwidth

In generally, microwave absorption and shielding are a pair of conjugate properties, which merely achieves in the same system of electro-magnetic materials. In this work, Prussian blue analogues (PBA) derived hollow CoNi@C frames embedding with reduced graphene oxide (rGO) are successfully synthesized through a facile self-assembly method. In addition to considerable dielectric loss originating from high conductivity components of C@rGO, magnetic loss is also impressive due to the dynamic magnetic coupling interaction among the closely spaced magnetic units of CoNi. Finally, the CoNi@C@rGO composite with an extremely low loading ratio of 30 wt% reveals a strong reflection loss of − 48 dB and a broad absorption bandwidth of 6.24 GHz concurrently at a thin thickness of 1.6 mm. The launch field is obviously suppressed by covering the CoNi@C@rGO coating and RCS is below − 10 dBm2 within the entire detection angles (−90°<theta<90°). Meanwhile, superior shielding effectiveness (SE) of 66.2 dB is also achieved in the CoNi@C@rGO composite at 3.59 mm. It demonstrates that our work provides an effective and facile approach to make a transformation between microwave absorption and microwave shielding in the same material system.

Enhanced magnetoelectric effect in Lead-Free piezoelectric BaZr0.2Ti0.8O3 − 0.5 Ba0.7Ca0.3TiO3 and Fe-rich magnetostrictive Co0.8Fe2.2-xDyxO4 nanocomposites for energy harvesting applications

The design, discovery and development of magnetoelectric (ME) composites with enhanced properties and performance opens up further opportunities to explore new scientific aspects and to develop next-generation electromagnetic devices. Nevertheless, the engineered complex ME composites with multi-phase interfacial chemistry have rarely been reported. In this context, in the present work, enhanced magnetoelectric phenomenon reported for the ME-composites made using lead-free ferroelectric phase BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 (BZT-BCT) and magnetostrictive phase Co0.8Fe(2.2-x)DyxO4 (CFDO). The ME composites were synthesized by varying the magnetostrictive CFDO phase, where Dy(x) varied as x = 0.000(ME1), 0.025 (ME2), 0.050 (ME3) and 0.075 (ME4). The effect of varying CFDO phase on the structure, morphology, microstructure, density, piezoelectric, dielectric, ferroelectric and magnetoelectric properties of the ME-composites is evaluated. X-ray diffraction analyses of all ME-composites confirm the tetragonal structure of the BZT-BCT ferroelectric phase and spinel cubic structure of the CFDO ferrimagnetic phase. Raman spectroscopic analyses also confirm and validate the respective phases with a clear signature presence of the characteristics modes. Granular, dense microstructure with a uniform particle size distribution evidenced in scanning electron microscopy imaging analyses. The physical density measurements indicate that the ME composites attain a density in the range of 6.0–6.4 g/cm3; density increases with increasing CFDO phase. Frequency dispersion profiles of the dielectric constant exhibit a maximum dielectric constant for ME1 composite while a sharp decrease in dielectric constant at higher frequencies is noted with increasing CFDO phase in the ME-composites. Ferroelectric properties evaluated by measuring the polarization (P) – electric field (E) hysteresis loops at 300 K indicate the presence of typical P-E loops in all ME composites confirming that the ferroelectric properties are retained even after combining with the magnetic phase. The ME4 composite demonstrate a 0.573 squareness ratio, which is useful for multistate memory device applications. The ME4 composites further characterized by a moderately higher remnant polarization (Pr = 2.24 µC/cm2). All the synthesized ME-composites are promising for permanent memory storage device (FeRAM) applications. Piezoelectric coefficient measurements indicate a maximum piezoelectric coefficient of 116 pC/N for the ME4 composite while the ME-coefficient measurements demonstrate higher ME-coefficients of 250 mV/(cm-Oe) for ME2 composite. Based on the comprehensive and comparative studies of the ME-composites with variable magnetostrictive phase, the structure-chemistry-property correlation in these ME-composites established for possible applications in electromagnetic devices and energy harvesting applications.

Investigation of structural, magnetic and dielectric properties of novel magnetoelectric ceramic composite system Ba0.9Ca0.1Fe12O19- Na0.5Bi0.5TiO3

Novel magnetoelectric ceramic composites (x)Ba0.9Ca0.1Fe12O19 + (1-x)Na0.5Bi0.5TiO3 (x = 0.10,0.20,0.30,0.40 and 0.50) were synthesized. XRD patterns were fitted with Rietveld method and it was revealed that there is coexistence of hexagonal P63/mmc phase along with rhombohedral R3c phase. The microstructural evaluation indicates the presence of hexagonal grains with average sizes of about 1 to 4 μm. The M − H hysteresis loop reflect ferromagnetic behavior of composites having coercivity (Hc) value around 400-900Oe. By increasing (Ba,Ca)Mwt% there is monotonic increase in both Ms and Mr, which confirms the formation of desired stoichiometry of relative phases for all the compositions. The variation of dielectric constant (έ) and dielectric loss (tanδ) with temperature were investigated for understanding conduction mechanism. For low BaMwt%, the resistance of the samples is high except BCNBT-5, which increases resistance again. BCNBT composites show NTCR nature and the resistance is much greater to its constituents and even greater to BaM-NBT composite.

Inducing ferromagnetism and magnetoelectric coupling in the ferroelectric alloy system BiFeO3–PbTiO3 via additives

There is a growing interest in BiFeO3-based alloys because of the possibility it offers for developing high-temperature high-performance piezoelectric materials and for their interesting multiferroic properties. Often such ceramics are synthesized with additives either to reduce/suppress leakage current that the system inherits from the parent compound BiFeO3 or to promote sintering via formation of the liquid phase. We demonstrate here the propensity for stabilizing ferromagnetism in the ferroelectric solid solution BiFeO3–PbTiO3 (BF–PT) when synthesized with additive MnO2. Detailed investigation revealed that the ferromagnetic property of the ceramic is extrinsic and caused by the additive enabled precipitation of trace amount of the ferrimagnetic Pb-hexaferrite phase, not easily detected in conventional x-ray diffraction measurements. We also show that the ferromagnetic property is induced in Co-modified BF–PT. However, in this case, the additive stabilizes the CoFe2O4 spinel ferrite phase. While our findings offer a strategy to develop particulate magnetoelectric multiferroic composites using additive assisted precipitation of the ferrimagnetic phase(s) in BiFeO3-based ferroelectric alloys, it also helps in better understanding of the electromechanical response in BFO-based alloys.

Nonlinear Stress dependent Resonant Studies on Press-fit ME Composites

Considering the wide applications of magnetoelectric (ME) composites in sensors, actuators, and microelectronic devices, optimizing them for the maximum ME coupling response has recently sought great attention among researchers. The coupling response of ME composites is maximum when operated in resonance conditions. In this article, a two-dimensional coupled in-plane formulation is proposed based on the in-plane vibrational theory to capture the resonant ME response of Press-fit ME composites. The study is extended to analyze the effect of stress and temperature on the resonant ME response of press-fit ME composites. The proposed theoretical formulation is validated experimentally and found to agree with each other. The numerical analysis is performed using the commercially available finite element software COMSOL® utilizing the Frequency Domain Perturbation study steps. The study reveals a nonlinear decrement in the peak resonant ME response with respect to both externally applied pre-stress and temperature conditions.

Electrical and Magnetoelectric Properties of Particulate Composites and Laminated Trilayered Thick‐Film Composites

Hydraulic pressing and screen printing methods are used to create particulate magnetoelectric composites and laminated trilayered thick‐film composites. X‐ray diffraction studies reveal the presence of cubic spinel and tetragonal perovskite structures for individual powders of ferrite CuFe2O4 and ferroelectric‐phase PbZr0.58Ti0.42O3. The dielectric constant of particulate composites decreases with increasing frequency around 1 MHz and beyond that frequency, a saturation state is attained. However, for laminated films, the dielectric constant decreases up to 1 MHz and then increases. The maximum dielectric constant at low frequency for particulate CuFe2O4/PZT composites is around 72.2, whereas for laminated CuFe2O4/PZT/CuFe2O4 composites it is 4.97 and for PZT/CuFe2O4/PZT composites is 5.24. Loss tangent exhibits the same trend as dielectric constant with frequency, which is explained by space charge polarization and is consistent with Koop's phenomenological theory. The dielectric constant's variation with temperature describes the contribution of electric dipoles to polarization and both composites exhibit absorption peaks. The semiconducting nature of both particulate and laminated composites can be seen in the DC resistivity graph with frequency and as frequency increases, DC resistivity decreases for both composites, which is explained by the small polaron‐hopping phenomenon. The magnetoelectric coupling effect for particulate composites (44 mV Oe−1cm−1) is also found to be small when compared to laminated trilayered composites (CuFe2O4/PZT/CuFe2O4—105 mV Oe−1cm−1 and PZT/CuFe2O4/PZT—68 mV Oe−1cm−1).

Exotic role of poling protocol on augmentation of magnetoelectricity in BCZT/CNZF layered composites

Here, we report exotic role of electrical poling of layered BCZT-CNZF bulk composite for a sustainable advancement of magnetoelectric (ME) technology. Practically, it seems quite difficult to access full potential of ME composites due to their weak ME coupling performances. Using a standard poling protocols, we successfully deployed coupling performance of laminated ME composite, comprises of ferroelectric (FE) layer of BCZT and a ferrite layer of CNZF. However, the ME coupling constant of laminated composite is optimized by lowering volume fraction of FE component to strengthen the mechanical strain in piezoelectric layer, while fixing the thickness of the magnetostrictive ferrite layer. Here, we employed systematic zero field cooled (ZFC) and field cooled (FC) electrical poling protocol on morphotropic phase boundary (MPB) based BCZT composition, well-appreciated for it’s remarkable electromechanical activity. We report a record augmentation in magnetoelectric coupling as a consequence of prudent field cooled poling mechanism. On the basis of our findings, we emphasize that the degree of magnetoelectricity may be significantly improved for miniaturization of efficient devices via proper execution of poling technique.

Magnetoelectric MEMS Magnetic Field Sensor Based on a Laminated Heterostructure of Bidomain Lithium Niobate and Metglas.

Non-contact mapping of magnetic fields produced by the human heart muscle requires the application of arrays of miniature and highly sensitive magnetic field sensors. In this article, we describe a MEMS technology of laminated magnetoelectric heterostructures comprising a thin piezoelectric lithium niobate single crystal and a film of magnetostrictive metglas. In the former, a ferroelectric bidomain structure is created using a technique developed by the authors. A cantilever is formed by microblasting inside the lithium niobate crystal. Metglas layers are deposited by magnetron sputtering. The quality of the metglas layers was assessed by XPS depth profiling and TEM. Detailed measurements of the magnetoelectric effect in the quasistatic and dynamic modes were performed. The magnetoelectric coefficient |α32| reaches a value of 492 V/(cm·Oe) at bending resonance. The quality factor of the structure was Q = 520. The average phase amounted to 93.4° ± 2.7° for the magnetic field amplitude ranging from 12 to 100 pT. An AC magnetic field detection limit of 12 pT at a resonance frequency of 3065 Hz was achieved which exceeds by a factor of 5 the best value for magnetoelectric MEMS lead-free composites reported in the literature. The noise level of the magnetoelectric signal was 0.47 µV/Hz1/2. Ways to improve the sensitivity of the developed sensors to the magnetic field for biomedical applications are indicated.

Magnetic, mechanical, electrical properties and coupling effects of particle reinforced piezoelectric polymer matrix composites

The 0-3 polymer-based magnetoelectric (ME) composites have the advantages of easy preparation, low cost, good flexibility, environmental friendliness and biological affinity, etc., and have a wide range of applications prospect in the biomedical field, such as the biological microelectronics, nanomedicine technology treatment, bone tissue healing and so on. The ME performance of this composite is jointly contributed by the properties of its component and microstructure. In this work, considering the impact of interphase effect, and the relationship between the effective properties of 0-3 ME composites and its microstructure is established, and the expressions of the Young's modulus, permeability, dielectric coefficient, piezoelectric coefficient, piezomagnetic coefficient and ME coefficient are obtained respectively. The effects of interphase properties and particle sizes on the effective properties of ME composites are discussed. By comparison, our theoretical results are in good agreement with experimental data. Then the influence of some factors on its effective performance is discussed. The results show that the effective properties of 0-3 ME composites are strongly dependent on the volume fraction ratio and size of the particles, the applied magnetic field. There is an optimal volume ratio and magnetic field to maximize ∂ α E 33 /∂ H 3 .

Магнитоэлектрические датчики тока: обзор

The article provides a review of various magnetoelectric composites that were studied in the current measurement mode. Recent studies have been conducted with both open- and closed-type structures. A comparison of the currently available ME current sensors is given. The study of closed ME structures will make it possible in the future to use them as current sensors and implement on their basis a contactless system for measuring both high and low currents.

The magnetopyroelectric effect: heat-mediated magnetoelectricity in magnetic nanoparticle-ferroelectric polymer composites.

Magnetoelectricity enables a solid-state material to generate electricity under magnetic fields. Most magnetoelectric composites are developed through a strain-mediated route by coupling piezoelectric and magnetostrictive phases. However, the limited availability of high-performance magnetostrictive components has become a constraint for the development of novel magnetoelectric materials. Here, we demonstrate that nanostructured composites of magnetic and pyroelectric materials can generate electrical output, a phenomenon we refer to as the magnetopyroelectric (MPE) effect, which is analogous to the magnetoelectric effect in strain-mediated composite multiferroics. Our composite consists of magnetic iron oxide nanoparticles (IONPs) dispersed in a ferroelectric (and also pyroelectric) poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) matrix. Under a high-frequency low-magnitude alternating magnetic field, the IONPs generate heat through hysteresis loss, which stimulates the depolarization process of the pyroelectric polymer. This magnetopyroelectric approach creates a new opportunity to develop magnetoelectric materials for a wide range of applications.

Методы увеличения магнитоэлектрического эффекта в композитных структурах: обзор

The article provides a review of various methods that can be used to increase the magnetoelectric (ME) effect in composite structures based on magnetostrictive and piezoelectric materials. It is shown that the use of adhesive technology and gradient structure, as well as thermal and thermomagnetic treatment of a magnetostrictive amorphous alloy of an ME structure make it possible to achieve a significant increase in the ME effect. To date, great efforts have been made to optimize the strain amplitude in the piezoelectric and magnetostrictive phases of multilayer ME materials. The use of various technologies in the manufacture of ME composites makes it possible, for example, to increase the sensitivity of magnetic field sensors for biomedical applications. Also, an increase in the ME effect opens up great prospects for further research.