压电复合振子谐振频率的磁调控研究  

Magnetically tuned mechanical resonances in piezoelectric composite vibrator

作　　者：茹媛[1] 邵雪[2] 赵浩[1] 黄婉晴[2] 潘鹏飞[1] 王巍[1] 

机构地区：[1]南京师范大学物理科学与技术学院,南京210023 [2]南京师范大学教师教育学院,南京210023

出　　处：《南京大学学报（自然科学版）》2015年第6期1126-1131,共6页Journal of Nanjing University（Natural Science）

基　　金：2014年南京师范大学大学生实践创新项目

摘　　要：压电超声换能器中,压电振子谐振频率的漂移是导致换能器输出功率降低和振幅不稳定的主要原因.利用稀土超磁致伸缩材料Tb-Dy-Fe(TDF)合金与压电陶瓷材料Pb(Zr,Ti)O3(PZT)构成磁电复合压电振子,基于磁致伸缩材料的ΔE效应及复合材料的磁-力-电耦合乘积作用,实现了直流磁场对压电复合振子谐振频率的实时调控.实验结果表明,在直流磁场的作用下,压电复合振子的谐振频率随磁场的增加发生明显偏移.当磁场强度为400mT时,谐振频率的最大偏移量约为15kHz.利用磁电耦合理论,数值模拟谐振频率随磁场的偏移与实验结果符合较好.同时,理论研究了磁致伸缩相的体积分数对磁场调控谐振频率偏移的影响.结果表明,随着磁致伸缩相体积分数增加,谐振频率随磁场的偏移逐渐加大.该研究为压电超声换能器中控制谐振频率漂移提供理论及实验基础,并为提高磁调谐灵敏度提供有效途径.Resonant frequency shift of ultrasonic transducers is common phenomena in the application of high power piezoelectric ultrasonic transducers,which results in poor power conversion and poor amplitude.In this paper,based on magnetostrictive material Tb-Dy-Fe （TDF）and piezoelectric ceramics Pb （Zr,Ti）O3 （PZT）layer composite vibrator,magnetically tuned mechanical resonances were achieved with ΔE effect of magnetostrictive material and magnetoelectric coupling product effect.The interaction between an external magnetic field and the polarization of pi-ezoelectric materials is one way to achieve such a magnetodielectric effect （ME）.It was found that the resonant frequency of piezoelectric composite vibrator significantly shifts with increasing dc magnetic field,which resonant frequency offset were about 15 kHz when the magnetic field intensity was 400 mT.Both in magnetoelectric coupling theory and experiment result,the frequency shift with dc magnetic field has the same behavior.Besides,thenbsp;relationship between the volume fraction of magnetostrictive material and resonant frequency shift were also presented.Experimental and theoretical analysis showed that such magnetically tuned variation in resonant frequency originated from the magnetic field-induced change of the compliances of the magnetostrictive phase.The results show that the resonant frequency offset increase gradually with the increase of magnetostrictive phase volume fraction.Because of large frequency shift and high sensitivity,the present magnetically tuned resonant frequency can be widely used in magnetic sensors,ultrasonic transducers.As we have used only dc magnetic field that tuned elec-tromechanical resonances,the adj ustment manner can simplify application in ultrasonic transducers.

关 键 词：压电复合振子 磁电耦合 谐振频率 

分 类 号：O424[理学—声学]