Study On The Performance Of Multilayer Piezoelectric Substrate Laminated Magnetoelectric Composite

Magnetoelectric composites are novel muti-functional materials, which are synthesized by combining piezoelectric and piezomagnetic materials together. These composites have good direct magnetoelectric effect (DME) and converse magnetoelectric effect (CME) achieved by the interaction between magnetism and electricity. This dissertation focuses on the DME and CME of the magnetoelectric composite Pb(Zr,Ti)O3(PZT) multilayer vibrator and magnetostrictive materials to improve the magnetoelectric sensitivity and CME conversion.First, we researched the DME and CME in the composite of PZT multilayer vibrator and Terfenol-D. The composite has a high magnetic field sensitivity of15nC/Oe at the magnetoelectric coefficient of9.5V/cmOe, which can detect0.1mOe magnetic field. Converse magnetoelectric coefficient reaches46.5G/V for the whole sample and74G/V at the middle of composite. These high qualities were achieved when a Pb(Zr,Ti)O3single-layer were substituted by Pb(Zr,Ti)O3multilayer vibrator in the piezoelectric part which has its much larger capacitance, larger effective area and lower thickness. This approach provides a promising application for the magnetoelectric materials.Second, we researched the magnetoelectric effect of multilayer vibrator and piezomagnetic Ni plate. By comparing with the front experiment, we found that Ni composites had lower bias magnetic fields, which is beneficial for the experiments and application. What’s more, Ni has a low price and is easily machined. A magnetoelectric theoretical model combining the piezoelectric and piezomagnetic parts about the longitudinal vibration was proposed for the laminate composite based on equivalent circuit. The model shows that the magnetoelectric voltage is relative to the thickness ratio, total thickness, frequency and loss. A simple laminate magnetoelectric composite was prepared by bonding a nickel plate and a multilayer piezoelectric vibrator together for the experimental research. The multilayer vibrator has high capacitance, large effective area and low thickness, leading to a high magnetic field sensitivity of1mOe. At the magnetoelectric coefficient reached2.58V/cmOe in the simple composite with the nickel thickness of0.2mm. The model fits well with the resonance frequency of the experimental results. The numerical calculation well predicates the magnetoelectric experimental behaviors, presenting a magnetoelectric maximum at about the thickness ratio0.3between the nickel plate and multilayer vibrators. This approach provides a method for the magnetoelectric application.Finally, we also studied the magnetoelectric sandwiched composite of PZT multilayer/Terfenol-D/PZT multilayer in detail. The results of experiment show that the resonance frequency of sandwich structure sample can be observed near the49kHz,whi ch is lower than that double-layer structure sample (53kHz), due to the conductive adhesive. Furthermore, magnetoelectric coefficient of sandwich structure sample is1.49V/cmOe, resulting the decrease of magnetoelectric properties. The phenomenon attribut e to the unideal Piezomagnetic phase Terfenol-D property in the experiment.We studied the magnetoelectric properties with the bias magnetic fields, frequency and thickness of the sample and so on. We found that the magnetoelectric efficient can reach9.5V/cmOe under the resonance frequency.