Magnetoelectric Composites Research Articles

Investigation of structural, optical, electrical and magnetic properties of magnetoelectric composite of NiFe2O4 and YMnO3

Magnetoelectric composites of Nickel Ferrite and Yttrium Manganite (xNiFe2O4 – (1-x) YMnO3, x = 0.25 and 0.50) were prepared using solid state reaction method. Their structural, optical, magnetic and electric behavior was studied by X-ray diffraction (XRD), UV–Vis spectroscopy, vibrating sample magnetometer (VSM), dielectric and polarization versus electric field (P-E) measurement at room temperature. Coexistence of the both ferrite and ferroelectric phases in the composites was confirmed by X-ray diffraction. Structural analysis had shown that lattice strain corresponding to nickel ferrite (NFO) phase was increased while for Yttrium Manganite (YMO) it was not much affected after formation of composites. The values of direct band gap for the composite came out to be larger than that for YMnO3 (1.43 eV) and smaller than that for NiFe2O4 (1.74 eV). Existence of ferromagnetic ordering in the composites was confirmed by VSM. Value of saturation magnetization was found to be highest in nickel ferrite (46 emu/g) and it was decreased with increase in concentration of ferroelectric phase in the composites. The sample with 75% YMO has shown highest dielectric constant (∼700) among all the four samples. P-E loops were not saturated and polarization current was found mainly due to conduction of charge carriers.

Boosting energy harvesting of fully flexible magnetoelectric composites of PVDF-AlN and NiO-decorated carbon nanofibers

The increasing popularity of wearable electronics has sparked interest in flexible energy harvesters as alternatives to conventional batteries. Flexible magnetoelectric (ME) composites, known for converting ambient magnetic field energy into useable power, are emerging as promising autonomous energy sources for integration into wearable devices. In this study, we prepared flexible (PVDF-AlN)–(NiO–CNF) based ME composites using two different methods: solution-casting and electrospinning techniques. The ME coupling was confirmed by measuring the ferroelectric and magnetic properties of the composite, and it was qualitatively characterized through the ME coupling coefficient. The electrospinning fibers-based ME composite exhibited an optimal value of 10.6 V/cm.Oe, significantly higher than the solution-casting films-based ME composite (1.3 V/cm.Oe) under a 1 kHz AC magnetic field (off-resonance condition). Subsequently, a flexible magneto-mechano-electric (MME) generator was designed using electrospun-derived material, harvesting a sinusoidal wave with a maximum output peak-to-peak voltage of 9.02 V. The generator displayed an optimal DC power density of 97 μW/m2 when exposed to a weak AC magnetic field of 6 Oe at a frequency of 50 Hz. Consequently, it holds great promise as an efficient autonomous power supply for medical sensing and various miniature electronic applications.

Modeling and performance analysis of resonant self-biased magnetoelectric transducers

Compared with single-phase multiferroic materials, magnetoelectric (ME) composites composed of piezoelectric and magnetostrictive materials have great ME coupling, and have received widespread attention in various application fields. The application of ME devices in wireless power transfer (WPT) is attractive due to their compactness and ability to operate at lower frequencies than conventional coils. However, traditional ME composites rely on permanent magnets or electromagnets to provide biased magnetic fields, thus leading to problems such as high noise, large size, and high cost, which significantly hinder the advancement of miniaturized and high-performance ME devices. To solve this problem, a self-biased ME laminated structure based on the magnetization grading effect is proposed in this work. Using the equivalent magnetization and nonlinear magnetostrictive constitutive relationship, a finite element simulation model for a self-biased ME transducer operating in L-T mode is constructed. The ME coupling performances without DC bias in bending vibration mode and stretching vibration mode are studied. Based on the model, the corresponding experimental samples are prepared for measurement. The measurement results are in agreement with the simulation data, thereby validating the accuracy and effectiveness of the model. The measured results show that the Metglas/Galfenol/PZT-5A structure can exhibit more significant self-biased ME effect under the stretching resonance mode than under bending resonance mode. Its ME coefficient attains a notable value of 10.7 V·cm<sup>–1</sup>·Oe<sup>–1</sup> at 99.4 kHz, while ME power coefficient reaches 5.01 μW·Oe<sup>–2</sup> at 97.9 kHz. Its on-load ME power coefficient can reach up to 4.62 μW·Oe<sup>–2</sup> at 99.3 kHz without impedance matching. When an external bias magnetic field of 25 Oe is applied, these performance indexes increase significantly to 47.06 V·cm<sup>–1</sup>·Oe<sup>–1</sup> at 99.4 kHz and 82.13 μW·Oe<sup>–2</sup> at 99.0 kHz, respectively. The simulation results further show that the performance of the self-biased ME transducer can be significantly improved by increasing the thickness of the high permeability layer. For example, by increasing the Metglas layer thickness from 30 μm to 90 μm, both the ME coefficient and ME power coefficient increase rapidly by 2.47 times and 6.96 times the original values, respectively. Self-biased ME transducers effectively reduce the dependence on external bias magnetic field, thereby providing a good approach for applying and developing ME composites in low-frequency WPT systems.

Advances in magnetoelectric composites for promoting bone regeneration: a review.

Repair of large bone defects is one of the clinical problems that have not yet been fully solved. The dynamic balance of bone tissue is regulated by many biological, chemical and physical environmental factors. Simulating the microenvironment of bone tissue in the physiological state through biomimetic materials is an important development direction of tissue engineering in recent years. With the deepening of research, it has been found that when bone tissue is damaged, its surrounding magnetoelectric microenvironment is subsequently destroyed, and providing a magnetoelectric microenvironment in the biomimetic state will be beneficial to promote bone repair. This review describes the piezoelectric effect of natural bone tissue with magnetoelectric stimulation for bone regeneration, provides a detailed account of the historical development of magnetoelectric composites and the current magnetoelectric composites that are most commonly utilized in the field of tissue engineering. Besides, the hypothesized mechanistic pathways through which magnetoelectric composite materials promote bone regeneration are critically examined, including the enhancement of osteogenesis, promotion of cell adhesion and angiogenesis, modulation of bone immunity, and promotion of nerve regeneration.

Symmetric Equivalent Circuit Theory and Numerical Simulation Analysis of Nonlinear Magnetoelectric Laminated Composite

In order to further study the nonlinear characteristics of the resonance magnetoelectric coefficient and vibration mode at the resonance frequency, three-layer magnetoelectric composite with length direction magnetization and thickness direction polarization is investigated in the article. Firstly, based on the Z-L model and the numerical solution characteristics of magnetization intensity, the magnetization intensity function was fitted, and the dynamic parameters of the giant magnetostrictive material, including dynamic piezomagnetic coefficient, dynamic elastic compliance coefficient, and dynamic magnetic permeability, were further derived. The effects of bias magnetic field and prestress on the corresponding composite were analyzed; Secondly, based on the nonlinear magnetostrictive constitutive equation, a symmetric magneto-elastic-electric equivalent circuit model of magnetoelectric laminate composite was established, and the expression of magnetoelectric coefficient was derived. The variation curve with bias magnetic field and prestress was analyzed, which is consistent with the conclusions of existing literature [8] and [9]; Finally, in order to compare with the theoretical results, the same parameters were set using COMSOL software, and the corresponding magnetoelectric coefficient frequency curve was plotted. The two results were in good agreement, and the maximum peak modal vibration shape was extracted, which can conveniently observe the vibration of the magneto electric laminate composite in the length direction. The results indicate that the theoretical model of this symmetric magneto-elastic-electric equivalent circuit and the numerical simulation method using COMSOL software are feasible, laying the foundation for further nonlinear analysis of magnetoelectric laminate composite and making it possible to design high-precision magnetoelectric micro devices.

Robust multiferroicity and magnetic modulation of the ferroelectric imprint field in heterostructures comprising epitaxial Hf0.5Zr0.5O2 and Co.

Magnetoelectric multiferroics, either single-phase or composites comprising ferroelectric/ferromagnetic coupled films, are promising candidates for energy efficient memory computing. However, most of the multiferroic magnetoelectric systems studied so far are based on materials that are not compatible with industrial processes. Doped hafnia is emerging as one of the few CMOS-compatible ferroelectric materials. Thus, it is highly relevant to study the integration of ferroelectric hafnia into multiferroic systems. In particular, ferroelectricity in hafnia, and the eventual magnetoelectric coupling when ferromagnetic layers are grown atop of it, are very much dependent on quality of interfaces. Since magnetic metals frequently exhibit noticeable reactivity when grown onto oxides, it is expected that ferroelectricity and magnetoelectricity might be reduced in multiferroic hafnia-based structures. In this article, we present excellent ferroelectric endurance and retention in epitaxial Hf0.5Zr0.5O2 films grown on buffered silicon using Co as the top electrode. The crucial influence of a thin Pt capping layer grown on top of Co on the ferroelectric functional characteristics is revealed by contrasting the utilization of Pt-capped Co, non-capped Co and Pt. Magnetic control of the imprint electric field (up to 40% modulation) is achieved in Pt-capped Co/Hf0.5Zr0.5O2 structures, although this does not lead to appreciable tuning of the ferroelectric polarization, as a result of its high stability. Computation of piezoelectric and flexoelectric strain-mediated mechanisms of the observed magnetoelectric coupling reveal that flexoelectric contributions are likely to be at the origin of the large imprint electric field variation.

Exchange bias mediated self-biased magnetoelectric coupling in Co–BaTiO3 composites

The magnetoelectric composites of ferromagnetic cobalt (Co) with various morphologies and ferroelectric BaTiO3 (BTO).

AC Current Sensor Based on Magnetoelectric Composites Transducers: Resonance Damping, Current Dynamic and Electric Field Disturbances

AC Current Sensor Based on Magnetoelectric Composites Transducers: Resonance Damping, Current Dynamic and Electric Field Disturbances

Magnetoelectric behaviour of Pb-free Na0.5Bi0.5TiO3-Ni0.5Co0.5Fe2O4 particulate novel ceramic composites

Magnetoelectric (ME) multiferroic composites are more promising candidates for low-power consumption devices, next-generation spintronic devices, and multistate memory devices since they exhibit significantly higher Magnetoelectric interaction over single-phase multiferroics. In this regard magnetic behaviour, dielectric, and magnetoelectric characteristics of a novel Pb-free (1-x) Na0.5Bi0.5TiO3-(x) Ni0.5Co0.5Fe2O4, (x = 0, 0.2, 0.4, 0.6, 0.8 & 1) particulate composites were explored. Solid-state synthesis was adopted to prepare the single-phase Na0.5Bi0.5TiO3 (NBT), Ni0.5Co0.5Fe2O4 (NCFO), and their composites. The presence of rhombohedral NBT and cubic inverse spinel NCFO in the composites were confirmed with X-ray diffraction (XRD) patterns. Microstrain (ε) induced in the prepared samples was estimated by using the Williamson-Hall (W-H) method. The piezoelectric NBT phase shows the tensile strain and the ferromagnetic NCFO shows the comprehensive strain. Among all the composites 0.8NBT-0.2NCFO shows a higher strain value of 0.012%, and the decrement in the strain values was observed upon increases in ferrite concentration. Backscattered scanning electron microscope (BS-SEM) images revealed the existence of highly dense uniformly distributed elements and Energy dispersive spectroscopy (EDS) confirmed the existing elements in the composites. UV–vis absorbance spectra disclosed a rise in energy gap values from 1.14 eV to 3.0 eV with increasing NBT percentage. Variations of dielectric permittivity and dielectric loss with respect to AC frequency were studied at room temperature (RT), and the 0.2NBT-0.8NCFO sample shows a high dielectric permittivity of 8500 at ∼100Hz. M − H (Magnetization-Magnetic field) hysteresis loops demonstrate the pure ferrite phase has a coercive field (Hc) = 578 Oe, remnant magnetization (Mr) = 21.43 emu/g and saturation magnetization (Ms) = 71.29 emu/g. The Ms and Mr values in the composites are enhanced with increasing ferrite percentage. Studies on ME behaviour of (1-x) NBT-(x) NCFO, (x = 0.2,0.4,0.6 & 0.8) show the coupling effect between both the phases at room temperature and the highest coupling coefficient value 3.16mV/Cm. Oe was observed for the 0.8NBT-0.2NCFO further the reasons and mechanisms are discussed.

FRACTURE ANALYSIS AND SHIELDING EFFECTS IN ADVANCED MATERIALS

Due to their ability to interconnect electrical and mechanical domains, piezoelectric materials are increasingly finding applications in advanced electromechanical systems. Notably, magneto-electric composites like BaTiO3-CoFe2O4 have emerged as vital materials for the next generation of devices. Exploring this realm is a complex and significant endeavor, demanding the attention of the scientific community and further research. Over recent decades, the scope of formulating and executing computational models for continuous media has substantially broadened, encompassing a diverse array of material properties and fields in computational models. This article centers on the utilization of asymptotic analysis as a mathematical tool for constructing approximate equations and assessing the relevance of various hypotheses. It delves into the utilization of the perturbation method, pioneered by Kagadiy T. S. and others, to tackle two-dimensional contact problems in electropelasticity, particularly in the context of materials with linear anisotropy. The extensive applicability of this asymptotic approach underscores its efficacy in simplifying intricate problems by breaking them down into a sequence of boundary problem resolutions grounded in the theory of potentials. The collaborative effort of the authors in this research underscores that employing the mentioned method opens up avenues for formulating pertinent boundary problems for the fundamental equations. This, in turn, allows for the representation of the initial electropelasticity problem as a superposition of more manageable boundary problems. While mechanical and electrical components can be treated separately, they still interact via boundary conditions. To conduct a numerical analysis, the article examines scenarios where one crack surface slides parallel to the crack front against another and selects relevant materials with known characteristics. Calculations reveal that, even in the absence of mechanical load, crack surfaces undergo relative sliding due to non-zero electrical or magnetic fields. The study of the shielding effect, which mitigates crack motion by altering magnetic field distribution, holds particular significance. This effect reduces the overall stress intensity factor and impedes crack propagation. Conducting such a comprehensive analysis is pivotal for comprehending and foretelling the strength and reliability of structural components composed of piezoelectric and piezomagnetic materials. It is imperative to conduct a thorough examination of the mechanisms governing their failure.

Microstructural and physical characterizations of (1-x)(0.67BiFeO3+ 0.33BaTiO3+ 1%MnO2)− x(CoFe2O4+ 3%ZnO) magnetoelectric composites

BiFeO3 (BFO) was mixed with BaTiO3 (BTO) to form a solid solution of large piezoelectric coefficient (d33) for the fabrication of magnetoelectric (ME) composites with the Zn-doped CoFeO4 (CFO). The 0.67BFO+0.33BTO solid solution, which was doped with 1 at% MnO2 for lowering leakage current, showed a high d33 of 121 pC/N. However, in the composites made with CFO, a much lower d33 (<42 pC/N) was retained. The microstructure of the composites was featured by the large CFO grains (∼5 μm) embedded in the 0.67BFO+0.33BTO matrix of much finer grains (∼0.5 μm). The CFO grains each had a well-defined morphology with clear boundary discriminating them from the neighboring piezoelectric phase. Both the CFO and piezoelectric grains showed a high crystallinity as indicated by the appearance of clear Kikuchi patterns in electron backscattered diffraction. After reducing DC conductivity of CFO by Zn-doping and the optimization of fractional ratio of the Zn-doped CFO in the composites, a ME voltage coefficient of 81.8 mV/cm-Oe was achieved, which was high among the lead-free particulate ME composites prepared by the conventional solid-state sintering.

Resonant Magnetoelectric Coupling of Fe-Si-B/Pb(Zr,Ti)O3 Laminated Composites with Surface Crystalline Layers.

The resonant magnetoelectric (ME) effect of Fe78Si9B13/Pb(Zr,Ti)O3 (FeSiB/PZT) composites with a surface-modified Fe78Si9B13 amorphous alloy has been studied. The surface-modified FeSiB can improve the ME coefficient at the resonant frequency by optimizing the magnetomechancial power conversion efficiency. The maximum ME coefficient of the surface-modified ribbons combined with soft PZT (PZT5) is two-thirds larger than that of the composites with fully amorphous ribbons. Meanwhile, the maximum value of the ME coefficient with surface-modified FeSiB ribbons and hard PZT (PZT8) is one-third higher compared with the fully amorphous composites. In addition, experimental results of magnetomechanical coupling properties of FeSiB/PZT composites with or without piezoelectric layers indicate that the power efficiency of the composites first decreases and then increases with the increase in the number of FeSiB layers. When the surface crystalline FeSiB ribbons are combined with a commercially available hard piezoelectric ceramic plate, the maximum magnetoelectric coupling coefficient of the ME composite reaches 5522 V/(Oe*cm), of which the electromechanical resonant frequency is 23.89 kHz.

High SNR magnetoelectric sensor with dual working modes for wideband magnetic field detection

Magnetoelectric (ME) composites exhibit extremely high sensitivity for magnetic field at the fixed resonant frequency, due to the strong strain-mediated ME coupling. However, wideband magnetic field detection is still challenging, as the ME coefficient depends strongly on the frequency. In this work, we propose a magnetoelectric sensor composed of three ME units in series/parallel connections, which works at dual modes to extend the frequency range with high signal-to-noise ratio (SNR). The SNR is enhanced by about 22.68 dB and the bandwidth is broadened from 100 Hz to 1 kHz, with a high sensitivity for frequency conversion mode by series/parallel connections. Limits of detections (LoDs) as low as 207 pT and 460 pT are demonstrated at 1 kHz and 100 kHz, respectively, showing promising applications in wideband magnetic field detection.

Detection of inhomogeneous magnetic fields by magnetoelectric composite

Magnetoelectric (ME) composites can be useful due to their wide range of possible applications, especially as sensors of weak magnetic fields at room temperature for magnetocardiography and magnetoencephalography techniques in medical diagnostic equipment. In most works on the topic of ME composites, structures are tested in uniform magnetic fields; however, for practical application, a detailed consideration of the interaction with inhomogeneous magnetic fields (IMF) is necessary. In this work we made measurements of IMF with radial symmetry of individual thin wire with AC voltage with different placements of ME sensor. A ME self-biased structure b-LN/Ni/Metglas with a sensitivity to magnetic field of 120 V/T was created for IMF detection. The necessity of external biasing magnetic field is avoided by a nickel layer and its remanent magnetization. ME composite shows a non-zero ME coefficient of 0.24 V/(cm·Oe) in absence of DC external magnetic field. It is shown that output voltage amplitude from ME composite, which is located in AC IMF, is dependent from relative position of investigated sample and magnetic field lines. Maximum ME signal is obtained when long side of ME sample is perpendicular to the wire, and symmetry plane which divides the long side in two similar pieces contains an axis of the wire. In frequency range from 400 Hz to 1000 Hz in absence of vibrational and other noises a limit of detection has value of (2 ± 0.4) nT/Hz1/2.

A Flexible Magnetic Field Sensor Based on PZT/CFO Bilayer via van der Waals Oxide Heteroepitaxy.

Magnetoelectric (ME) magnetic field sensors utilize ME effects in ferroelectric ferromagnetic layered heterostructures to convert magnetic signals into electrical signals. However, the substrate clamping effect greatly limits the design and fabrication of ME composites with high ME coefficients. To reduce the clamping effect and improve the ME response, a flexible ME sensor based on PbZr0.2Ti0.8O3 (PZT)/CoFe2O4 (CFO) ME bilayered heterostructure was deposited on mica substrates via van der Waals oxide heteroepitaxy. A saturated magnetization of 114.5 emu/cm3 was observed in the bilayers. The flexible sensor exhibited a strong ME coefficient of 6.12 V/cm·Oe. The local ME coupling has been confirmed by the evolution of the ferroelectric domain under applied magnetic fields. The flexible ME sensor possessed a stable response with high sensitivity to both AC and DC weak magnetic fields. A high linearity of 0.9988 and sensitivity of 72.65 mV/Oe of the ME sensor were obtained under flat states. The ME output and limit-of-detection under different bending states showed an inferior trend as the bending radius increased. A flexible proximity sensor has been demonstrated, indicating a promising avenue for wearable device applications and significantly broadening the potential application of the flexible ME magnetic field sensors.

A low-frequency vibration energy harvester employing self-biased magnetoelectric composite

Global energy shortage puts stringent demand for energy harvesters capable of transforming external green vibration sources into electrical power. Employing a self-biased magnetoelectric (ME) composite of FeCuNbSiB/Ni/PZT (lead zirconate titanate), a prototype of vibration energy harvester is designed and fabricated. The energy harvester has a circular orbit in which a permanent magnetic cylinder reciprocates once an initial kinetic energy is provided. Upon a vibration signal, like handshaking, movement of the permanent magnetic cylinder causes an alternative magnetic field, which was applied on the ME composite. Via magnetic-force-electrical coupling, the ME composite of FeCuNbSiB/Ni/PZT produces output voltage. Finite element simulation is carried out to reveal the underlying mechanism of the harvester. The analysis shows that a maximum output voltage of 7.63 V can be obtained once an original potential energy is applied for the magnet. In particular, the magnet moves back and forth automatically inside the circular orbit with no need to further apply the energy. The effectiveness of the energy output is experimentally verified. When handshaking the energy harvester, a maximum open-circuit voltage of 5.51 V can be generated. The study offers a solution for power supplying some miniaturized or portable devices, such as small hand set and pedometer.

Contactless sensor for real-time monitoring of lithium battery external short circuit based on magnetoelectric elastomer composites

The frequent accident due to external short circuit of lithium-ion batteries in electric vehicles have prompted people to develop sensing technology to achieve early warning. However, the limited space and high temperature in highly integrated lithium-ion battery packs present significant challenges for current sensors to achieve external short circuit monitoring with high structural flexibility and heat resistance. In this study, a piezoelectric elastomer is designed and blended with magnetostrictive ferric tetroxide to prepare the LMPE/Fe3O4 magnetoelectric current sensor (LMPE/Fe3O4 MCS). The amorphous structure and low modulus of the piezoelectric elastomer enable the LMPE/Fe3O4 MCS to exhibit large deformability over 50 % elongation, and the non-ferroelectric LMPE and ferric tetroxide with high Curie temperature offer the LMPE/Fe3O4 MCS with high heat resistance over 150 °C. Meanwhile, the excellent interfacial interaction between the piezoelectric elastomer and the ferric tetroxide eliminates stress transfer loss between the interface, presenting outstanding magnetoelectric response and excellent linearity (>0.99) with current sensitivity of 5.975 mV A−1. The LMPE/Fe3O4 MCS can achieve real-time monitoring and early warning for external vibration and short circuit during the charging and discharging process of lithium batteries, which shows promising solutions for the safety improvement of electric vehicles.

Magnetoelectric coupling optimization in lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 and Ni0.5Zn0.5Fe2O4 nanocomposites for magneto-mechano-electric generator

Magneto-mechano-electric (MME) generators efficiently harness ubiquitous stray magnetic fields and convert them into electricity, capturing significant attention for powering innumerable wireless sensors. In this study, lead-free 0-3 particulate magnetoelectric (ME) nano-composite ceramics, specifically x(Ba0.85Ca0.15Zr0.1Ti0.9O3)-(1-x)Ni0.5Zn0.5Fe2O4 [x(BCT-BZT)–(1-x)NZFO], were synthesized using the sol-gel method. Subsequently, a flexible MME generator was designed, incorporating the optimized ME composite. Structural parameter calculations indicated higher tetragonal distortion of 0.4% in 0.4(BCT-BZT)-0.6NZFO, possibly due to uniform particulate distribution. The ME composites displayed uniform dual-phase microstructures, with 0.4(BCT-BZT)-0.6NZFO showing a higher NZFO concentration. The maximum values of the magnetodielectric (MD) and ME coupling coefficients have been determined to be -3.6% and 2.55 mV cm -1 Oe-1, respectively, for an x = 0.4 composite. The MME generator is designed using an optimized 0.4(BCT-BZT)-0.6NZFO ME composite with film thickness of 34 μm. This MME generator harvests a sinusoidal wave with a maximum output peak-to-peak voltage of 4.1 V when exposed to a weak AC magnetic field of 10 Oe at a frequency of 50 Hz. Additionally, the device demonstrates an exceptional optimal DC power density of 3.89 μW cm-3. The lead-free 0-3 particulate ME composite enables effective magnetic energy harnessing. As a result, it holds great promise as an efficient autonomous power supply for various Internet of Things based applications.

Parametric investigations of wireless energy transfer using strain-mediated magnetoelectric transmitter-receiver

Magnetoelectric (ME) composites inherently convert magnetic energy to electrical energy and vice-versa, making them a viable technology in wireless energy transfer (WET) applications. This article focuses on identifying the optimal configuration for achieving relatively high ME power conversion efficiency in a fully ME-based transmitter/receiver composite system. Two configurations of ME composites, one in concentric composite rings and the other in layered laminate formation, have been fabricated and used alternately as transmitters and receivers. The influence of three important parameters has been experimentally studied and reported, including the effect of (1) the magnetization state of the magnetostrictive components and (2) the relative orientation of and (3) the separation distance between the transmitter and the receiver. It has been found that a higher energy conversion efficiency is obtained in a configuration where the laminated plate was used as the transmitter while the ring composites acted as the receiver. Furthermore, the location and alignment of the receiver significantly influence the output transferred power. Lastly, the distance between the transmitter and the receiver has been observed to have an exponential inverse influence on the performance of the investigated WET system. These results have been deciphered by experimentally generating horizontal and vertical magnetic field mapping around the composite systems and capacitance measurement of the piezoelectric element. Thus, this article presents a detailed study of the parameters and their influence on the performance of the ME-based WET technology, which would be extremely useful in designing and optimizing devices based on this technology.

Data-Driven oriented diatomic doping strategy to customize frequency dispersion for considerable microwave absorption

The electromagnetic (EM) parameters are the key factors to decode the complex microwave absorption properties, including matching thickness, absorption bandwidth and intensity. Numerous works hence have been focused on optimizing EM parameters to reinforce the comprehensive absorption performance, while most of the adopted experimental means still remain in sporadic and random attempts. In this work, the data-driven approach is first employed to forecast that a fierce frequency-dispersion of permittivity is necessary for the broad absorption, and the appropriate magnetic component can mitigate this elusive trend of required permittivity. Oriented by the simulated results, the B/N diatomic doped C/Fe3C magnetoelectric composites are successfully constructed, aiming at the precise regulation of electronic properties to achieve these specially customized EM parameters by forming multi-polarization resonances. The results demonstrate that the introduction of N defects and B defects could enrich the types of dipole pairs (CN, C-B, CNB, vacancy, etc.) and thus activate multi-polarization behavior. The charge density differences calculated by the first-principle further demonstrate that the occupation of B for C bonded with Pyridinic-N and Pyrrolic-N contributes to intense polarization behaviors over the lower frequency range. As a result, excellent microwave absorption properties can be finally achieved with an effective absorbing bandwidth reaching 7.2 GHz at 2.1 mm, implying that the joint use of data-driven and doping engineering strategies to customize frequency dispersion characteristics provides precious guidelines for boosting microwave absorption performance.