A Study On The Structure And Properties Of Magnetoelectric Composite Materials

The lack of single-phase magnetoelectric（ME）materials and their low performance at room temperature make the ME composite due to the result that those materials become the ideal materials to prepare the new generation electronic devices.Piezoelectric/magnetostrictive composite materials have extensive and important applications in fields such as magnetic field sensors,magnetoelectric transducers,microwave devices,resonators,etc.due to their excellent force/electricity transfer function and rapid response characteristics,the key to obtaining a larger magnetoelectric coupling coefficient lies in the selection of suitable materials and device structures.In this paper,based on the nonlinear constitutive relation of the giant magnetostrictive material Terfenol-D,the finite element software Comsol was used to analyze the resonant frequency variation of the PZT/Terfenol-D/PZT composite under the bias magnetic field,and based on this design.Magnetoelectric sensors dedicated to gear speed sensing have been experimentally verified.This dissertation proposes a Z-type magnetoelectric device based on the structural design,then establishes a theoretical model of this structure.The results show that the longer the length of Terfenol-D,the shorter the length of PZT,and the greater the magnetoelectric effect of the Z-type device.At the same time,the experiment shows that the magnetoelectric coefficient of the device can reach 0.283V/cm×Oe at low frequency,and the magnetoelectric coupling performance is stronger than most magnetoelectric devices.Multi-functionalization and miniaturization are inevitable development trends of electronic devices.Multiferroic materials with multiple characteristics coexisting and coupled to each other have become a research hotspot.In this paper,the common ferroelectric material Pb(Zr_0.52Ti_0.48)O₃（PZT）and magnetostrictive material Ni_0.5Zn_0.5Fe₂O₄（NZFO）were composited.The PZT-NZFO composite magnetoelectric thin film was prepared by magnetron sputtering.In the preparation of the thin film,the nanocrystallization of the system grains and the uniform distribution of the two-phase crystal grains are achieved by controlling the sputtering power and time,the substrate temperature,and the sputtering ratio of argon to oxygen.The experimental results show that the substrate temperature of 800°C,oxygen partial pressure ratio of 0.4,sputtering power of 160W is more suitable for PZT-NZFO film growth.The SEM test results show that the thin film sputtered under this condition has a clear 1-3 dimensional nanostructure.Excessively high sputtering power will cause the 1-3 dimensional structure to change into an irregular 0-3dimensional structure,and the proper oxygen partial pressure ratio will contribute to the formation of the NZFO phase.When the substrate temperature is 800°C,the phases of PZT and NZFO are more obvious.If the temperature is raised further,Pb will be volatilized,which weakens the phase formation of PZT.