Research On The Magnetoelectric Coupling Effect Of The Laminated Magnetostrictive/Piezoelectric Composites

Design and explore the laminated magnetostrictive/piezoelectric composites materials are one of the electronic science research topics,which have remarkable magnetoelectric(ME)effect and achieve effective conversion between the magnetic field and electric field.Magnetoelectric effect can be applied to microwave devices,magnetic field sensors,“electric write and magnetic read” ME-RAM,compact ME antennas,spintronics and so on.It's generally believed that the ME effect in the composites is due to the strain mediated product effect between the magnetostrictive(MS)and piezoelectric(PE)materials.However,due to the complexity of the strain/stress distribution in the ME composites,there lack a regular understanding of the mechanism of the strain-mediated ME coupling in present researches.Theoretical and numerical simulation aims to establish an accurate model to analyze the coupling relation between the MS and PE materials,and make a further prediction of the ME effect with external factors,such as the magnetic field,pre-stress and temperature.In this paper,based on the laminated ME composites,the ME effect of the nonlinear magneto-elasto-electric coupling,the bending and extension coupling mode of the asymmetric laminated ME composites with elastic material layer,the size effect of the nano-ME thin film composites,the non-volatile magnetic properties and magnetization oscillation based on converse ME effect and both the ceramic ME composites are studied.The main contents and innovations of the full paper are as follows:Firstly,based on the nonlinear constitutive equations of giant MS materials and the equivalent circuit method,nonlinear magneto-elasto-electric coupling models are developed for Terfenol-D/PZT/Terfenol-D layered ME composite structures.The predicted results obtained by our theoretical model are in good agree with the experimental results.Then,based on the nonlinear coupling model,the ME effects of the static and resonant states under different pre-stress and bias magnetic field are predicted.The predicted results shown that choose a suitable pre-stress can be enhance the magnetoelecltric effect and decreasing the optimua bias magnetic field.Secondly,based on the asymptotic method,we further proposed a theoretical model for the ME effect in asymmetric multilayer ME composite with elastic layers in which the special bending and extension coupling mode are considered.The predicted results are compared with the experimental results to verify the applicability of the model.The influence of the basic parameters of the material and elastic layer on the ME effect and the resonance frequency of the coupled mode is studied.Simulation results shows that the ME effect is much complicated with the pizoeleletric volume fraction and the elastic layer thickness.And,the ME effect can be enhanced with a certain elastic layer thickness;the resonant frequency increasing with the increase of the elastic layer thickness.Thirdly,a theoretical study on the ME thin film composite with elastic layer has been proposed.The extended Gurtin-Murdoch theory is employed to describe the surface magnetostriction effect and surface piezoelectric effect of the MS and PE materials,respectively.Then,the influence of the surface effect and the elastic layer on ME coefficient and resonant frequency is studied.The results show that the surface effect can increase the ME coefficient and can be ignored when the surface layer to bulk thickness ratio is small enough.Fourthly,in order to reveal the magnetization states of magnetic materials in ME composites and the evolution of magnetization reversal with applied voltage,we applied the theory of micro-magnetic and the finite element method,and a multi-physics coupling model of ME composite material is established.Combining with the shape anisotropy and ME effect of the magnetic element,the physical mechanism of the magnetization rotation controlled by the electric field is discussed.The control process of the magnetization state by the applied pulse voltage was simulated by FEM software.The related magnetization distribution diagram and thermodynamic analysis results clearly show that the magnetic element realizes unidirectional and non-volatile 180° magnetization switching under two pairs of DC pulse voltages.Based on the concept of the DC voltage control magnetization switching in the strain mediated ME composites,the mechanism of magnetization oscillation driven by AC voltage are proposed and a ME composite structures is developed.The FEM simulation results show that the frequency of the magnetization oscillation is the same as the frequency of the applied AC voltage,and the linewidth of the stable magnetization oscillation is smaller than the magnetic field driven oscillation.Finally,a preliminary exploration of the ceramic ME composites based on the LTCC and tape casting technology was constructed.And,the nonlinear ME effect model proposed in this paper was used to analyses the ME coupling mechanism of the ceramic ME composites based on the experiment results.The comparison between the experiment results and predicted model confirms that the nonlinear ME coupling model presented in this paper is suitable for the study of various strain-meditated laminated ME composites.In summary,this research applied the method of theoretical derivation,numerical analysis and FEM simulation to the ME composites and studied the physical mechanism of magneto-mechanical-electric coupling in ME composites and to explore the basic rules.Furthermore,a preliminary study of the laminated ME ceramic composites are based on the LTCC and tape casting technology with aid of the theoretical models.These researches provide further improvement of the ME coupling theory,and important theoretical guidance for the design and optimization of ME sensors,electric field control devices and spintronic devices based on the ME effect.