Magnetoelectric Performance Research Articles

Bath temperature effect on magnetoelectric performance of Ni–lead zirconate titanate–Ni laminated composites synthesized by electroless deposition

Magnetoelectric (ME) Ni–lead zirconate titanate–Ni laminated composites have been prepared by electroless deposition at various bath temperatures. The structure of the Ni layers deposited at various bath temperatures was characterized by X-ray diffraction, and microstructures were investigated by transmission electron microscopy. The magnetostrictive coefficients were measured by means of a resistance strain gauge. The transverse ME voltage coefficient α E,31 was measured with the magnetic field applied parallel to the sample plane. The deposition rate of Ni increases with bath temperature. Ni layer with smaller grain size is obtained at higher bath temperature and shows higher piezomagnetic coefficient, promoting the ME effect of corresponding laminated composites. It is advantageous to increase the bath temperature, while trying to avoid the breaking of bath constituents.

Frequency response of magnetoelectric 1–3-type composites

A three-phase magnetoelectric (ME) composite consisting of Pb(Zr,Ti)O3 rods embedded in a matrix of Terfenol-D/epoxy (TDE) pseudo 1–3 composites has been fabricated. Besides the large ME effect, its frequency response under a magnetic bias field has been studied. It was found that the resonance shifts to lower frequency with increasing bias field. Due to the magnetomechanical characteristics of the TDE pseudo 1–3 medium, the composite shows a similar trend in ME performance. Magnetic-field dependence of the frequency shift provides a means to tune the performance of ME sensors based on the composite.

Magnetoelectric Performances in Composite of Piezoelectric Ceramic and Ferromagnetic Constant-Elasticity Alloy

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A high-quality factor magnetoelectric (ME) laminated composite employing a type of ferromagnetic constant-elasticity alloy (FCEA) and piezoelectric Pb(Zr,Ti)O<formula formulatype="inline"><tex Notation="TeX">$_{3}$</tex></formula> material is developed. The laminate is designed to operate as a half-wavelength <formula formulatype="inline"><tex Notation="TeX">$(\lambda/2)$</tex></formula>, longitudinal resonator. The FCEA features high effective quality factor and low magnetomechanical coupling coefficient. This induces a particular ME characteristic. The theoretical analysis shows that the ME voltage coefficient (MEVC) at low frequency is directly proportional to the product of the electromechanical coupling factor in piezoelectric layer, magnetomechanical coupling factor, and the square root of magnetic permeability in FCEA layers. The MEVC at resonance and the ME sensitivity (under resonant drive) to dc bias magnetic field <formula formulatype="inline"> <tex Notation="TeX">$(H_{\rm dc})$</tex></formula> are dramatically increased by the effective quality factor <formula formulatype="inline"><tex Notation="TeX">$(Q_{m})$</tex> </formula> of the resonator. The measured vibrational characteristics reveal that the strain coefficient at resonance achieves 314.74 nm/A and <formula formulatype="inline"><tex Notation="TeX">$Q_{m}$</tex></formula> is <formula formulatype="inline"><tex Notation="TeX">${\sim} 1600$</tex></formula>. The MEVC at resonance <formula formulatype="inline"><tex Notation="TeX">$(\alpha_{r})$</tex> </formula> achieves 30.55 V/Oe (381.875 V/cm Oe), which is 1608 times higher than that at low frequency. In addition, <formula formulatype="inline"><tex Notation="TeX">$\alpha_{r}$</tex></formula> strongly depends on <formula formulatype="inline"> <tex Notation="TeX">$H_{\rm dc}$</tex></formula> due to the high <formula formulatype="inline"><tex Notation="TeX">$Q_{m}$</tex></formula>, e.g., <formula formulatype="inline"><tex Notation="TeX">$\partial \alpha_{r}/\partial H_{\rm dc}$</tex></formula> achieves 0.84 V/Oe<formula formulatype="inline"><tex Notation="TeX">$^{2}$</tex></formula>. The ME resonator is potential for highly sensitive dc or quasi-static magnetic field sensing. </para>

Resonant modes and magnetoelectric performance of PZT/Ni cylindrical layered composites

Resonant modes and magnetoelectric performance of layered PZT/Ni and Ni/PZT/Ni cylindrical composites are considered. The first and the second resonant frequencies in the 1–150 kHz range correspond to the axial and the radial modes. Experimental results and theoretical analysis indicate that one should choose the trilayered structure and the first resonant frequency as the working frequency. This study is helpful in design and applications of magnetoelectric devices.

Geometry effects on magnetoelectric performance of layered Ni/PZT composites

Layered magnetoelectric (ME) composite structures of varying geometry consisting of PZT and Ni layers were prepared by electrodeposition. Trilayered plate, bilayered and trilayered cylindrical structures’ ME performance was compared. The ME voltage coefficient increased with Ni layer thickness. Cylindrical composites show better ME performance than the plate structures with the same magnetostrictive-piezoelectric phase thickness ratio under high applied magnetic fields at resonant frequencies. Bilayered cylindrical Ni/PZT structure has the best performance in axial mode under high magnetic field, exhibiting linear ME voltage coefficient dependence on the applied magnetic field, which makes it a promising candidate for magnetic field sensor applications. Cutting the ring along the axial direction drastically decreased its performance.

Electro-deposition current density effect on Ni/PZT layered magnetoelectric composites performance

This paper considers the magnetoelectric (ME) effect in Ni/PZT layered ME composites that is related to the preferred crystallographic orientation of electro-deposited Ni layers. The Ni electro-deposition rate increases with applied cathodic current density. High (1 0 0) texture in the Ni layer was obtained at either low or high current densities, which improves the ME composite's performance. It is advantageous to increase the current density, while trying to avoid hydrogen evolution during electro-deposition to reduce the number of pinhole defects.

The resonant magnetoelectric response of magnetostrictive/piezoelectric laminated composite under the consideration of losses

The theoretical analysis of resonance magnetoelectric(ME) performances in longitude-transverse type magnetostrictive/piezoelectric laminated composite is presented in this paper based on the equivalent circuit method, and the formula of ME voltage coefficient is obtained, which is useful to the composite design and optimization. To evaluate the ME voltage coefficient near the resonance, the losses such as eddy-current loss, mechanical loss, and dielectric loss are considered and formulated, which indicates that the mechanical loss plays the key role in dissipation. The analysis, which takes losses into account, gives better explanations to current experimental values.