ME Composites Research Articles

Fe-enriched two-phase multiferroic composites based on lead ferroniobate - titanate and modified nickel ferrite

Iron-enriched ferroelectrics are of particular interest as piezoactive components of piezoelectric-ferrite ME ceramics. This is due to the phase composition similarity and the reduction of expected interfacial doping effects during high-temperature calcination. This idea seems attractive, but laborious due to the significantly limited number of possible piezoelectric–ferrite combinations. Therefore, there is practically no data on such systems in the literature. ME composite ceramics based on the highly efficient Fe-containing Pb(Fe0.5Nb0.5)0.935Ti0.065O3 (PFNPT) ferroelectric has been studied. (100-х) wt.% Pb(Fe0.5Nb0.5)0.935Ti0.065O3 (PFNPT) + х wt.% Ni0.9Co0.1Cu0.1Fe1.9O4-d (NCCF) composite systems has been obtained by the solid-state method at 1050 °C, with no foreign phases. The specimens densities amounted to ∼80% of the theoretical. It has been shown that the ME conversion efficiency and other composites properties are significantly influenced by the PFNPT precursor pre-treatment method. The maximum value of the ME coefficient ΔΕ/ΔΗ = 75 mV/(cm Oe) has been observed for specimens with x = 50–60 made from PFNPT powder with the addition of Li2CO3. An increase in the ME composites sintering temperature to 1150 °C leads to the formation of Pb2Nb2O7 foreign phase with a pyrochlore structure along the grain boundaries. The ME coefficient ΔΕ/ΔΗ does not exceed 15 mV/(cm⋅Oe). There is an threefold decrease in the composites piezoelectric parameters (piezoelectric coefficients dij, gij), as well as in their magnetic properties (magnetizations MS, MR) due to piezophase degradation, which is presumably associated with a change in the cations distribution over A and B sublattices of the spinel structure.

Strain‐Sensitive Flexible Magnetoelectric Ceramic Nanocomposites

AbstractMagnetoelectric (ME) oxide materials can convert magnetic input into electric output and vice versa, making them excellent candidates for advanced sensing, data storage, and communication. However, their application has been limited to rigid devices due to their brittle nature. Here, flexible ME oxide composite (BaTiO3/CoFe2O4) thin film nanostructures with distinct ME coupling coefficients are reported. In contrast to rigid bulk counterparts, these ceramic nanostructures display a flexible behavior after being released from the substrate, and can be transferred onto a stretchable substrate such as polydimethylsiloxane. These ceramic films possess high ME coefficients due to minimized clamping effect and preferred crystalline orientation, and exhibit reversibly tunable ME coupling via mechanical stretching thanks to their large elasticity (>4%). It is believed that the study can open up new avenues for integrating ceramic ME composites into micro‐/nanoelectromechanical system and soft robotic devices.

Исследование магнитоэлектрических продольно-сдвиговой и крутильной мод в несимметричных структурах

The theoretical study of possibility for the torsional mode identification against the background of longitudinal-shear one in asymmetric ME composites Metglas / GaAs and Metglas / bimorph LN Zyl + 45° is carried out in this paper. It is determined that ME composites with bimorph LN Zyl + 45° are better to use as a piezoelectric to study the torsional mode of the ME effect. This is due to the fact that the longitudinal-shear mode is not excited in the ME composite with a bimorph LN Zyl + 45°, and the ME voltage coefficient depends only on the torsional mode.

Low Frequency Magnetoelectric Sensor Without Bias Using Laminated Metglas/Quartz/Metglas Structure

Tremendous progress has been made on boosting the performance of magnetoelecric sensor to detect low frequency magnetic field signal by frequency multiplication based on magnetolectric composites. In this paper, a novel magnetoelectric sensor based on the laminated Metglas/piezoelectric quartz crystal/Metglas composites structure is presented. The Metglas foils are bonded symmetrically on both sides of the X-cut quartz crystal plate with epoxy. Experiments showed that the ME composites sensor was able to achieved a limit of detection of 11 pT for a low frequency magnetic field 1 Hz without any bias field through frequency multiplication method. The noise power spectrum density of the sensor has also been tested to be 3.93·10-6 V/Hz1/2 at 1 Hz. The results indicate that the proposed sensor has favorable features, which provides a cost-effective and high-performance approach for low frequency magnetic field measurement. Keywords: Low frequency, limit of detection, magnetoelectric sensor, piezoelectric quartz crystal.

Exotic magnetic properties and enhanced magnetoelectric coupling in Fe3O4-BaTiO3 heterostructures

In the present work, magnetoelectric composites of Fe3O4 and BaTiO3 were successfully synthesized with 0–3 and 1–3 connectivity. In Fe3O4-BaTiO3 composites with 1–3 connectivity, the M-H loop analysis shows the presence of the isotropic point, whereas the M-T measurements of both samples reveal a unique downturn anomaly in the Curie-Weiss plot, indicating the presence of a Griffiths-like phase. The cluster glass nature of Fe3O4 nanostructures leads to the formation of exchange bias in the investigated ME composites. The different phase transitions of BaTiO3 are visible in the M(T) data as a consequence of magnetoelectric coupling between Fe3O4 and BaTiO3. The maximum magnetoelectric coupling coefficients observed for the Fe3O4-BaTiO3 composites with 0–3 and 1–3 connectivity are 8.34 mV cm−1 Oe−1 and 28.78 mV cm−1 Oe−1, respectively; both values are higher than that of the previously reported values of Fe3O4-BaTiO3 composites. Further, the magnetoelectric coupling coefficients of Fe3O4-BaTiO3 1–3 composites show an increasing trend towards the BaTiO3 rich phase.

Structural, magnetic, magneto-dielectric and magneto-electric properties of (1-x) Ba0.85Ca0.15Ti0.90Zr0.10O3 – (x) CoFe2O4 lead-free multiferroic composites sintered at higher temperature

Here in this article synthesis of lead-free magnetoelectric composites (1-x) Ba0.85Ca0.15 Ti0.9Zr0.1)O3 - xCoFe2O3 (BCTZ-CFO, x = 0.4, 0.5, and 0.6) is reported. Structural, magnetic, dielectric, magnetodielectric and magnetoelectric properties of lead-free BCTZ-CFO composites sintered at higher sintering temperature have been systematically investigated. The piezoelectric (ferroelectric) phase has been synthesized using the sol–gel route, while Metallo-organic decomposition (MOD) route was employed to prepare piezomagnetic (ferrite) phase. The structural and microstructural properties were studied using X-Ray diffraction and Scanning electron Microscope respectively acknowledged the presence of two distinct phases as ferrite and ferroelectric in composite samples. The dense microstructure and larger average grain size were observed for samples with higher ferrite phase content. Long-range magnetic order was observed under magnetic study for all-composites. The magnetic properties enhanced for composites prepared with higher ferrite phase content. Dielectric properties were studied at room temperature and enhanced dielectric constant has been observed for samples with higher ferroelectric phase content, while minimum dielectric loss was observed for sample with 50/50 ferrite/ferroelectric phase composition. The magnetodielectric response has been also investigated for all ME composites. Leakage current characterization has been also discussed at and above the room temperature. The magneto-electric coupling response was measured of all composites. The higher value of magneto-electric coupling coefficient has been observed for 0.5BCTZ-0.5CFO composite due to maximum possible ferrite-ferroelectric hetero-structure phase contact area.

Низкочастотный магнитоэлектрический датчик без смещения на основе слоистой структуры Metglas/кварц/Metglas

Tremendous progress has been made on boosting the performance of magnetoelecric sensor to detect low frequency magnetic field signal by frequency multiplication based on magnetolectric composites. In this paper, a novel magnetoelectric sensor based on the laminated Metglas/piezoelectric quartz crystal/Metglas composites structure is presented. The Metglas foils are bonded symmetrically on both sides of the X-cut quartz crystal plate with epoxy. Experiments showed that the ME composites sensor was able to achieved a limit of detection of 11 pT for a low frequency magnetic field 1 Hz without any bias field through frequency multiplication method. The noise power spectrum density of the sensor has also been tested to be 3.93·10-6 V/Hz−1/2 at 1 Hz. The results indicate that the proposed sensor has favorable features, which provides a cost-effective and high-performance approach for low frequency magnetic field measurement.

Development of novel piezo-ionic/magnetostrictive composites for energy generation systems

Novel piezo-ionic/magnetostrictive bi-layer composites for new energy generation devices are presented. These structures, fabricated with Metglas® 2826MB ferromagnetic alloys and ionic liquid based PVDF-HFP polymer composites, show an induced electric response as a consequence of the coupling between the magnetostrictive properties of the Metglas® 2826MB and the piezo-ionic ones of the ionic liquid based PVDF-HFP polymer composites. These flexible, simple and low cost structures do not need to be polarized to exhibit an electric response, and show an increased induced voltage as the percentage of the ionic liquid in the PVDF-HFP matrix does. This response is a consequence of the asymmetric deformation caused by the magnetostrictive material on the piezo-ionic composite, which induces a non-uniform distribution of the cations and anions in the polymer matrix. The laminates present a maximum response under the application of a low magnetic fields of 9 Oe, and a normalized magneto-ionic coefficient values up to 550 mV cm−1.Oe for the structure with an ionic liquid content of 30 %. These values are even higher than others obtained with piezoelectric materials based ME composites. The simple fabrication process and potentiality of these new piezo-ionic/magnetostrictive laminates contributes to broaden and improve the state of the art of the energy generation systems.

Magnetoelectric Composites: Modeling and Application

The progress in electronic technology is directly coupled with the advances made in materials science. Within the broad class of materials available today, functional materials provide unique opportunity for developing novel components and devices as their physical and chemical properties. A combination of ferromagnetic and ferroelectric materials provides a new class of functional materials, termed as magnetoelectrics. An overview of modern magnetoelectric composites and examples of the design of electronic devices based on them are presented. The feature of these materials is that their parameters changes under the influence of an external magnetic and electric fields. The behavior of magnetoelectric composites in the wide frequency range is considered. Modeling of ME composites at low frequencies and in the field of electromechanical, ferromagnetic and magnetoacoustic resonances has shown that they can be effectively used to design various electronic devices in a wide frequency range. Nomographs method which can be used to plot the ME parameters versus initial material parameters and component volume fractions is presented. Nomographs can be used for a quick test of ME composites for applications where an approximate answer is appropriate and useful. Examples of ME composites application such as: magnetic field sensors, current sensors, microwave phase shifters, filters, attenuators, isolators are presented.

Enhanced strain derivative of Ho substituted cobalt ferrite and improved magnetoelectric coupling in co-sintered bi-layered ME composites

The magnetoelectric bilayer composites of Ho substituted cobalt ferrite as piezomagnetic phase and Sr, La modified PZT (PSLZT) as a piezoelectric phase were prepared to study magnetoelectric effect. The Ho substituted cobalt ferrite CoFe2-xHoxO4 where, x = 0.0, 0.01, 0.02, 0.03, 0.05 and 0.15, were successfully synthesized by sol-gel auto combustion method. The phase formation of synthesized Ho substituted cobalt ferrite series has been confirmed by using X-ray diffraction (XRD). For the samples up to x = 0.05 formation of single spinel ferrite phase and for higher concentration i.e. x = 0.15, along with spinel ferrite phase secondary ortho-ferrite phase have been observed. FTIR and Raman spectroscopic analysis has been carried out to confirm the presence of metal oxide functional group at tetrahedral and octahedral sites of spinel structure. Morphological analysis of all the samples under investigation has been carried out using Scanning Electron Microscopy. The magnetostrictive properties were measured at room temperature and the influence of Ho substitution on magnetostrictive properties of cobalt ferrite has also been investigated. Further, the strain derivative (dλ/dH) has been determined in order to understand the piezomagnetic properties of the samples. The strain derivative of Ho substituted cobalt ferrite attains maximum value at a low magnetic field with respect to cobalt ferrite which is useful in stress sensors applications. Finally, the magnetoelectric properties of PSLZT -Ho substituted cobalt ferrite layered composite structure have been investigated. The relation between magnetoelectric properties of the composites and piezomagnetic properties of the ferrite samples has been elucidated based on the theoretical model proposed in the literature by Bichurin et al.

Structural, dielectric and magnetic studies of ferrite-ferroelectric composites

The composites of ferrite-ferroelectric system (x) Mg0.2Cu0.5Zn0.3Fe2O4 + (1-x) BaTiO3 (x = 15%, 30% and 45%) were synthesized by sintering the mixtures of ferroelectric BaTiO3 (BTO) and ferrite component Mg0.2Cu0.5Zn0.3Fe2O4 (MCZF). Ferrimagnetic MCZF was prepared using auto-combustion method where as ferroelectric BTO was procured commercially from Sigma-Aldrich. The presences of two phases in magneto-electric composites were probed by X-ray diffraction (XRD) studies. The peaks observed in the XRD spectrum indicated spinel cubic structure for MCZF ferrite and tetragonal perovskite structure for BTO and, both spinel and pervoskite structures for synthesized composites. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). Frequency dependent dielectric properties of synthesized composites were measured from 100 Hz to 1 MHz at room temperature (RT) using HIOKI LCR HI-TESTER. The dielectric dispersion is observed at lower frequencies for the synthesized ME composites. The magnetic properties of synthesized composites were analyzed using a Vibrating Sample Magnetometer. It is observed that the composites exhibited magnetic hysteresis with narrow loops indicating the magnetic ordering in the composites. All the measurements were carried out at room temperature.

Electrical properties of novel (x) Ni0.5Zn0.5Fe2O4 + (1-x)PbZr0.8Ti0.2O3 ME composites

Magnetoelectric composites with composition (x)Ni0.5Zn0.5Fe2O4 + (1-x)PbZr0.8Ti0.2O3 (PZT- Lead Zirconate Titanate) in which x varies as 0.0, 0.15, 0.30, 0.45 and 1.0 mol % were prepared by the conventional double sintering ceramic technique. The phase analysis was carried out using X-ray diffraction technique, which confirms the absence of any intermediate phase present in the composites. Scanning electron micrographs (SEM) were taken to understand the surface morphology of the samples. The DC resistivity was measured as a function of temperature. The variation of dielectric constant (ε′) and loss tangent (tanδ) in the frequency range 20 Hz to 1 MHz was studied. The conduction phenomenon was explained on the basis of small polaron hopping model. The confirmation of this phenomenon was made with the help of AC conductivity measurements.

Rietveld refinement, dielectric and magnetic properties of NBT-Spinel ferrite composites

Ferrite-ferroelectric composites having general formula (1-x)Na0.5Bi0.5TiO3-(x)Ni0.25Mg0.5Zn0.25Fe2O4 were developed by conventional solid state reaction method. The structural, dielectric and magnetic properties were studied for all the prepared samples. The crystalline phases of samples were verified by XRD. Rietveld refinement pattern confirms the coexistence of cubic ferrite phase as well as rhombohedral ferroelectric phase in the composites which make them promising candidate for versatile applications. The tangent loss (tanδ) and dielectric constant (εʹ) both shows dispersion at lower frequencies. From the Nyquist plot of impedance, the effect of grain and grain boundaries on the electrical properties was examined. From Arrhenius plot, it was found that dc conductivity and activation energy of all the compositions increases with increase in temperature. Magnetic parameters were found to be increased as the ferrite phase is increased which provides information regarding the intercoupling between the ferroelectric and magnetostrictive ferrite phases. These ME composites are found to be useful in memory devices.

Temperature Dependent Electric Properties and Magnetoelectric Effects in Ferroelectric rich Ni0.8Mg0.2Fe2O4 + BaZr0.2Ti0.8O3 Magnetoelectric Composites

The magnetoelectric composites with the compositions of ferrites & ferroelectrics having the general chemical formula (x) Ni0.8Mg0.2Fe2O4 + (1-x) BaZr0.2Ti0.8O3 (in which x = 0.1, 0.2, 0.3) were synthesized by using double sintering ceramic technique. From XRD, the phase formation of ferrites with cubic structure and ferroelectrics with tetragonal perovskite structure was confirmed through the measurement of XRD. The two phase ME composites have larger saturation magnetization and dielectric constant; it is because of the effect of interfacial strain on BaZr0.2Ti0.8O3 ferroelectric phase. Furthermore, the ME response 4.262 mVcm−1Oe−1 was observed for (30%) Ni0.8Mg0.2Fe2O4 + (70%) BaZr0.2Ti0.8O3 composites at 5.0 kOe applied DC magnetic field; it shows the success of magnetic control of the dielectric response via the mechanical coupling which can be exploited in the future applications of multiferroic composites.

Theoretical modeling and experimental study of dielectric loss of the multi-push-pull mode magnetoelectric laminate composites

In this work, we establish a dielectric loss model for multi-push-pull mode ME laminate composites. It deduces that the total dielectric loss of the ME composites equals the linear average of the dielectric loss of piezoelectric plate and epoxy resin. But further analysis of this model has indicated that we can ignore the dielectric loss of epoxy resin. To verify this model, we use three kinds of epoxy resin with different dielectric loss to fabricate multi-push-pull mode PMNT/Metglas ME laminate composites respectively. It turns out that the different kinds of epoxy resin have little influence on the total dielectric loss, capacitance and piezoelectricity of the composites, which demonstrates that our model conforms to the practical case. Therefore, we can pay more attention to the mechanical properties of epoxy resin rather than its dielectric loss on fabricating the ME laminate composites.

Enhanced Resonance Magnetoelectric Coupling in (1-1) Connectivity Composites.

Bulk-magnetoelectric (ME) composites consisting of various piezoelectric and piezomagnetic materials with (3-0), (3-1), (2-2), and (2-1) connectivity are proposed in a bid to realize strong ME coupling for next-generation electronic-device applications. Here, 1D (1-1) connectivity ME composites consisting of a [011]-oriented Pb(Mg,Nb)O3 -PbTiO3 (PMN-PT) single-crystal fiber laminated with laser-treated amorphous FeBSi alloy (Metglas) and operating in L-T mode (longitudinally magnetized and transversely poled) are reported, which exhibit an enhanced resonant ME coupling coefficient of ≈7000 V cm-1 Oe-1 , which is nearly seven times higher than the best result published previously, and also a superhigh magnetic sensitivity of 1.35 × 10-13 T (directly detected) at resonance at room temperature, representing a significant advance in bulk magnetoelectric materials. The theoretical analyses based on magnetic-circuit and equivalent-circuit methods show that the enhancement in ME coupling can be attributed to the reduction in resonance loss of laser-treated Metglas alloy due to nanocrystallization and the strong magnetic-flux-concentration effect in (1-1) configuration composites.

Structural, Electrical and Magnetic Properties of Modified Bi<sub>1/2</sub>Na<sub>1/2</sub>TiO<sub>3</sub> - Modified CFO Based Magnetostrictive (Co<sub>0.6</sub>Zn<sub>0.4</sub>Fe<sub>1.7</sub>Mn<sub>0.3</sub>O<sub>4</sub>) Particulate Nanocomposite

Lead free Multiferroic composites that comprise Co0.6Zn0.4Fe1.7Mn0.3O4 (CZFMO) and 72.5(Bi1/2Na1/2TiO3)-22.5(Bi1/2K1/2TiO3)-5(BiMg1/2Ti1/2O3) (BNT-BNT-BMgT) were synthesized using sol-gel method and it’s structural, ferroelectric and magnetic properties were studied. The X-ray diffraction displayed the single phase formation of parent phases and the presence of two phases in the composites. The samples showed a well saturated polarization-electric field hysteresis loops. The remnant polarization and saturation polarization values are decreased with increasing ferrite content. Room temperature (RT) magnetic measurements show that composites are soft magnetic. The composite with x = 0.2, showed the enhanced magnetic and ferroelectric properties. Moreover, these ME composites provide a great opportunity as potential lead free systems for multifuntional device applications.

Synthesis and characterization of PZT: CF magnetoelectric composites

ABSTRACTHere, we report the structural, dielectric, ferroelectric, piezoelectric and magnetic properties of ME composites of Lead Zirconate Titanate (PZT) and Cobalt ferrite (CF) with compositional formula (1−x) PbZr0.55Ti0.45O3 + (x) CoFe2O4, (x = 0.00, 0.05, 0.10, 0.15 and 1.00 by weight). The samples were synthesized by conventional solid state reaction. The formation of perovskite tetragonal and spinel structure in the composites are confirmed by X-ray diffraction studies. Microstructural study of all samples was done by SEM analysis and average grain size was also calculated. The dielectric properties of samples were studied as a function of frequency and as a function of temperature (30°C – 500°C) respectively. P-E hysteresis loop at room temperature and piezoelectric coefficient were measured to study the ferroelectric and piezoelectric properties. To confirm the ferromagnetic behavior of the composites M-H hysteresis loop measurement was carried out. The Magnetoelectric voltage coefficient (dE/dH) was measured as a function of applied DC magnetic field. The maximum ME output of 389μV/ (cm.Oe) was observed for the composite with x = 0.15.

Effects of hysteresis and temperature on magnetoelectric effect in giant magnetostrictive/piezoelectric composites

A nonlinear dynamic hysteretic theoretical model on magnetoelectric effect of tri-layered composites is built based on a nonlinear constitutive relation for magnetostrictive material and a linear piezoelectric model for piezoelectric material. And a finite element analysis is implemented to investigate quantitatively the influences of hysteresis and temperature on the ME effect of the layered composites. The model also can explain the “self-biased” response caused by the hysteretic characteristics of the ME composites. Then the distribution of the true displacement along the longitudinal direction is revealed by numerical calculation. The increment of temperature due to the magnetic hysteresis loss is investigated. The temperature, the AC magnetic field and the bias field on the induced electric field and the ME effect are studied, respectively. The results show that the bigger the magnetic frequency, the larger the energy loss of the ME composites. The initial temperature has little effect on the induced electric field at low magnetic field region, but significant effect on the induced electric field at high magnetic field region. The frequency multiplying behavior will disappear when the bias field is strong. In addition, the bias magnetic field also affects the shape of E3∼HAC curve, with the increase of the bias field, the shape of E3∼HAC curve changes from symmetry to asymmetry. The frequency mixing of the induced electric field is also discussed.

Modeling of magnetoelectric composite nano-cantilever beam with surface effect

This work investigates the magnetoelectric response of a magnetostrictive–piezoelectric composite nano-cantilever beam with consideration of surface effects through the surface-layer-based model. The magnetoelectric composite nano-cantilever is treated as a bulk core plus two surface layers. The influences on the cantilever’s overall properties resulted from the surface effect is modeled as a spring force exerting on the boundary of the bulk core. A Kirchhoff’s theory is used to get the explicit solutions for the magnetoelectric effect of cantilever when subjected to bias magnetic field loads. In order to apply the appropriate boundary conditions on the cantilever, the effective axial force, shear force and moment are derived. Using the derived results, the so-called effective Miller–Shenoy coefficient, static and electromechanical resonance properties of the ME composite nano-cantilever beam for the extensional–bending coupling deformations are analyzed theoretically. At the same time, the effect of the substrate on ME effect is theoretically studied by altering the thickness of the substrate. The results indicate that the surface effects play a significant role in the magnetoelectric response of the ME composite nano-cantilever beam. This work is very helpful for design of nano-cantilever beam based devices and understanding the size-dependent properties of nanostructured ME composites in nano-electromechanical systems.