磁致伸缩材料与石英音叉复合低阻尼谐振磁电效应

Low-Damping Resonant Magnetoelectric Effect in the Composite of Magnetostrictive Alloy and Quartz Tuning Fork

采用磁致伸缩材料与石英音叉谐振器复合设计了一种低阻尼的谐振式磁电敏感单元。石英音叉工作在弯曲振动模式,音叉叉指结合区域(底部)产生的应力/应变方向相反、弯矩相互抵消,实际为解耦区域。将底部与磁致伸缩材料粘接复合设计谐振式磁电敏感单元的Q值主要取决于音叉谐振器自身的高Q值,磁致伸缩材料的高磁机阻尼被隔离。动态磁场作用下,磁-机-电转换过程可看作一个受迫振动过程,当激励磁场频率接近于音叉谐振频率时,输出电信号最大。实验结果表明:磁电敏感单元Q值高达5 034;谐振磁电电流系数达到799.2 nA/Oe;在接近谐振频率32.774 kHz信号激励下,磁电电流系数相对偏置磁场变化的灵敏度达到5 (nA/Oe)/Oe。

A low-damping resonant magnetoelectric(ME)sensitive unit is designed by using a magnetostrictive material and a quartz tuning fork resonator. The quartz tuning fork is operated in the bending vibration mode,and the direction of stress/strain occurred in the tines is opposite in the coupling area(i.e.,the bottom of the tuning fork),and the bending moments cancel each other out. The coupling area is actually the decoupling area of stress/strain. As the bottom of the quartz tuning fork resonator is bonded to the magnetostrictive material,the quality factor( Q -factor)of the resonant ME sensitive unit is mainly determined by the high Q -factor of the tuning fork resonator,and the magnetomechanical damping of the magnetostrictive material is isolated. Under the action of dynamic magnetic field,the magneto-mechanical-electrical conversion process can be regarded as a forced vibration process. When the frequency of the excitation magnetic field is close to the resonance frequency of the tuning fork,the output electrical signal achieves a peak. We fabricate a ME sensitive unit by employing FeGa alloy and a U shape tuning fork. The experimental results show that the Q -factor of the ME sensitive unit is as high as 5 034. The resonant ME current coefficient achieves 799.2 nA/Oe under the dc bias field 280 Oe. The sensitivity of the output ME current coefficient with respect to dc magnetic field is 5 (nA/Oe)/Oe when the ME sensitive unit is operated at the selected frequency around the resonance frequency of 32.774 kHz.