Showing papers by "Shuxiang Dong published in 2008"

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

Abstract: Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

Magnetoelectric Laminate Composites: An Overview

Abstract: Since the turn of the millennium, giant magnetoelectric (ME) effects have been found in laminated composites of piezoelectric and magnetostrictive layers. Compared with ME single phase and two-phase particulate composites, laminated composites have much higher ME coefficients and are also readily fabricated. Here, we will overview the brief history of ME laminates, discussing some of the important advancements in material couples, laminate configurations, and operational modes that have allowed for dramatic enhancements in the ME voltage and charge coefficients.

Multimodal system for harvesting magnetic and mechanical energy

Abstract: In this letter, we investigate a multimodal system for simultaneous energy harvesting from stray magnetic and mechanical energies by combining magnetoelectric and piezoelectric effects. The system consists of a cantilever beam with tip mass and a magnetoelectric laminate attached in the center of the beam. At 2 Oe magnetic field and mechanical vibration amplitude of 50mg, both at frequency of 20 Hz, the system was found to generate open circuit output voltage of 8 VP.P.. An equivalent circuit model is proposed that predicts a summation effect for both mechanical and magnetic energies.

Enhanced multiferroic properties of the high-valence Pr doped BiFeO3 thin film

Abstract: High-valence Pr-doped BiFeO3 (BPF) multiferroic thin film was prepared by pulsed laser deposition on a Pt∕TiO2∕SiO2∕Si substrate. X-ray diffraction analysis indicates that the BPF film is of pure phase with a polycrystalline perovskite structure. The BPF film exhibited enhanced multiferroic properties: (i) a rectangular-shaped electric hysteresis loop with a large Pr of 75μC∕cm2 and a low Ec of 250kV∕cm at Emax ∼620kV∕cm, (ii) a saturated magnetic hysteresis loop with a large Ms of 58emu∕cm3, and (iii) a fatigue-free behavior after being subjected to 1.2×109 switching cycles, which were superior to, in some aspects, those of La- or Nd-doped BiFeO3 films reported before.

Giant microwave tunability in FeGaB/lead magnesium niobate-lead titanate multiferroic composites

Abstract: Giant magnetoelectric coupling at both microwave frequencies and dc was observed in an FeGaB/lead magnesium niobate-lead titanate microwave multiferroic composite. A record high microwave frequency tunability of Δf=900MHz or Δf∕f=58% was demonstrated with the change of an external electric field from −6to+2kV∕cm. A strong electric field dependence of magnetic hysteresis loops was also observed. Such multiferroic composite provides great opportunities for electrostatically tunable microwave devices.

Equivalent circuit method for static and dynamic analysis of magnetoelectric laminated composites

Abstract: Magnetoelectric equivalent circuit analytical method is presented for laminate composites of magneto-strictive Terfenol-D (TbxDy1−xFe2) and piezoelectric Pb(Zr1−xTix)O3 (PZT) operated in longitudinal magnetized and transverse polarized (or L-T), and transverse magnetized and transverse polarized (or T-T) modes. Magnetoelectric (ME) couplings both at low-frequency and resonance-frequency have been studied, and our analysis predicts that (i) the ME voltage coefficients of both L-T and T-T modes increase with increasing the thickness of the piezoelectric phase whereas magnetostrictive phase thickness keeps constant, and then tend to saturation when the thickness ratio of piezoelectric phase to magnetic phases is >3; (ii) there are the optimum thickness ratios that maximize magnetoelectric (ME) voltage coefficients for the two modes, which are dependent on elastic compliances ratio of piezoelectric phase and magnetostrictive phase; and (iii) the ME voltage coefficients are dramatically increased by a factor of ∼Qm, when operated at resonance frequency. A series of Terfenol-D/PZT laminates were fabricated, and the results were compared with the theoretical ones. Experiments confirmed that equivalent circuit method is a useful tool for optimum designs of ME laminates.

Modeling and detection of quasi-static nanotesla magnetic field variations using magnetoelectric laminate sensors

Abstract: Laminated composites of magnetostrictive and piezoelectric layers have been developed for their magnetoelectric (ME) product tensor properties. In spite of the considerable progress in materials aspects, little attention has been given to ME laminate incorporation into a detection technology. Here, we present a ME technology including the laminate equivalent model, detection circuitry consideration and noise mitigation for ME laminate sensors operated at quasi-static (≤10 Hz) frequencies. We then constructed a passive magnetic field prototype sensor unit and detected a 2.6 nanotesla magnetic signal at 1 Hz frequency.

Thermal noise cancellation in symmetric magnetoelectric bimorph laminates

Abstract: We have found a symmetric Terfenol-D/Pb(Zr,Ti)03 (PZT) bimorph magnetoelectric (ME) laminate, which operates in a bending mode under an unsymmetrical (U-shaped) magnetic bias. It has a giant ME voltage coefficient of about 70V∕cmOe at resonance. Unlike other symmetric ME laminate structures, the symmetric bimorph structure has the capability to reject thermal noise from a magnetic signal, due to its back-to-back structure. The mechanism for the thermal noise cancellation capability is that the laminate operates in a bending mode (out charges of reverse sign), whereas the thermal noise is contained in a longitudinal mode (out charges have the same sign, allowing cancellation by differential detection).

A piezoelectric single crystal traveling wave step motor for low-temperature application

Abstract: A piezoelectric Pb(Mg1∕3Nb2∕3)O3-PbTiO3 single crystal traveling wave rotary motor operated in a stepping motion for cryogenic actuations was developed and characterized. This single crystal stepping motor had a torque of ⩾1.5kgcm, an excess of 1800 steps per revolution about its axis, and a power consumption of ≦2W by using a step motion with 25% duty cycle. We then show that this single crystal motor can successfully operate at 77K (liquid nitrogen) under a load.

Magnetoelectric laminate based DC magnetic field sensor

Abstract: We report on a DC magnetic field sensor that utilizes magnetoelectric (ME) laminate composites. It consists of a ring-dot piezoelectric transformer laminated to a magnetostrictive disc. When a constant voltage is applied to the ring section of the piezoelectric layer at resonance, a stress is induced in the dot section. Then, if an external magnetic object is introduced in the vicinity of the dot section, the effective elastic stiffness is increased, altering the resonance frequency. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

High power density magnetoelectric energy harvester

Abstract: Conventional methods for vibration energy harvesting are based on electromagnetic, electrostatic, piezoelectric and magnetostrictive mechanisms [1?4]. Among them, the magnetostrictive mechanism shows relative higher power density [4]. Here, we report energy harvesting mechanism based on magnetoelectric (ME) composites [5] made of high-permeability magnetostrictive FeBSiC alloy ribbons laminated with piezoelectric Pb(Zr,Ti)O3 (PZT) fibers. We will see that this multiferroic laminated composite has the potential to achieve higher power densities. Figure 1 illustrates the configuration of our ME energy harvester. In this design, two PZT fiber layer with multi symmetric polarization (push-pull) units are laminated with four magnetostrictive FeBSiC ones. It is suited for operating in both longitudinal (excited by a longitudinal magnetic field) and bending vibration modes (excited by mechanical vibrations).