A FeNi-based spring alloy/piezoelectric magneto-electrical composite material has been developed by the high mechanical quality factor of the FeNi-based spring alloy.Based on the equivalent circuit method,the relation between magneto-electric voltage coefficient,resonance frequency,mechanical quality factor,the maximal output power and the length ratio of magneto-strictive to piezoelectric layer is analyzed.Theoretical analysis and the experimental results indicate with increasing the length of FeNi-based spring alloy,the magneto-electric voltage coefficient,mechanical quality factor and the maximal output power increase and tend to constant,but resonance frequency decrease.

The dynamic magneto-mechanical behaviors in a type of iron-nickel-based ferromagnetic alloy with constant elasticity were investigated as a function of both the DC bias magnetic field (H-dc) and the frequency. The rectangular plate-like samples were excited to vibrate at a half-wavelength, longitudinal resonance by an AC magnetic field superimposed with various H-dc. The experimental results found that the strain coefficient at resonance reached 819.34 nm/A and the effective mechanical quality factor (Q(m)) was greater than 2000. The ratio of the maximum variation of the Young's modulus over H-dc to the value of the Young's modulus at a zero bias field was only similar to 0.8 parts per thousand because of the so-called constant elasticity. The resonant strain coefficients and Q(m) are strongly dependent on H-dc, which indicates a promising potential for use in DC and quasistatic magnetic field sensing.

To achieve strong power coupling, a resonance-type magnetoelectric (ME) transducer with high quality factor is developed to achieve strong ME coupling. The ME transducer employs a type of iron–nickel-based ferromagnetic alloy with constant elasticity and piezoelectric Pb(Zr,Ti)O3 (PZT8) material. The dynamic magnetomechanical behavior of the ferromagnetic alloy is investigated. The result indicates that the strain coefficient of the ferromagnetic alloy at resonance achieves 557.07nm/A due to the high effective mechanical quality factor of the alloy. The transducer is designed to operate as a half-wavelength, longitudinal resonator. The dynamic performance of the transducer is evaluated by measuring its electrical and vibrational characteristics. The results reveal that (1) the resonance of the transducer occurs at the frequency of 26.9336kHz with a strain coefficient of 314.74nm/A, an effective mechanical quality factor of 1600; (2) the ME voltage coefficient achieves 30.07V/Oe (i.e., 375.875V/cmOe) at resonance; (3) the ME output power density at optimal load resistance of 25kΩ achieves 0.956mW/cm3 under 0.3Oe root-mean-square AC magnetic field. The performances indicate that the transducer is promising for ME energy conversion application.

A high-quality factor magnetoelectric (ME) laminated composite employing a type of ferromagnetic constant-elasticity alloy (FCEA) and piezoelectric Pb(Zr,Ti)O$_{3}$ material is developed. The laminate is designed to operate as a half-wavelength $(\lambda/2)$, 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 $(H_{\rm dc})$ are dramatically increased by the effective quality factor $(Q_{m})$ of the resonator. The measured vibrational characteristics reveal that the strain coefficient at resonance achieves 314.74 nm/A and $Q_{m}$ is ${\sim} 1600$. The MEVC at resonance $(\alpha_{r})$ achieves 30.55 V/Oe (381.875 V/cm Oe), which is 1608 times higher than that at low frequency. In addition, $\alpha_{r}$ strongly depends on $H_{\rm dc}$ due to the high $Q_{m}$, e.g., $\partial \alpha_{r}/\partial H_{\rm dc}$ achieves 0.84 V/Oe$^{2}$. The ME resonator is potential for highly sensitive dc or quasi-static magnetic field sensing.

Magnetostrictive properties in a type of iron-nickel-based ferromagnetic alloy with constant elasticity (FeNi-FACE) are investigated. The results indicate that the strain coefficient at resonance achieves 865.70 nm/A due to the high effective mechanical quality factor (~3000) of the alloy. A magnetoelectric (ME) transducer with high effective mechanical quality factor is developed, which employs the FeNi-FACE and piezoelectric Pb(Zr,Ti)O3 (PZT8) material. The transducer is designed to operate as a half-wavelength (lambda/2), longitudinal resonator. Resonance of the transducer occurs at the frequency of 29.9674 kHz, and the resonant ME voltage coefficient achieves 35.707 V/Oe (i.e., 446.338 V/cm Oe) with an effective mechanical quality factor of 1450. The ME output power density at optimal load resistance of 35 kOmega arrives 0.989 mW/cm3 under 0.3 Oe root-mean-square AC magnetic field. The performances indicate that the ME transducer is promising for ME energy conversion application.