The Effect Of Close-looped Structure On Two Phase Magnetoelectric Laminate Composites

The development of society and science need new materials which have one or more properties of mechanical, electric, magnetic, optical, thermodynamic properties. Multiferroic materials which have attracted great interest recently exhibit more than one primary ferroic order parameter in a single material. Magnetoelectric material which is one of the multiferroic materials can produce a voltage under a magnetic field and recently stimulated much fundamental and application research interest due to potential applications in multifunctional devices. This paper wants to improve the magnetoelectric effect of the two phase magnetoelectric material by using the close-looped structure to avoid the demagnetization field. The main research work is:(1) The magnetostrictive material FeGa and high saturature magnetization material FeCoV were fabricated by induction melting and zone melting as the magnetic phase. Commercial BaTiO3, Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT) and Pb(Zr, Ti)O3(PZT) were used as piezoelectric phase. The measurement system was fabricated according dynamic method. X-ray, SEM, standard strain gauges et al were used to characterize the magnetoelectric composite materials.(2) FeCoV/PMN-PT laminate magnetoelectric composite materials was characterized and explained by the theory which have already reported. The samples of FeCoV/PMN-PT/FeCoV and Ni/PMN-PT/Ni sandwich thin film structure was fabricated and the result show that the magentoelectric effect of FeCoV/PMN-PT/FeCoV is five times larger than that of the Ni/PMN-PT/Ni structure and have a good candidate in ME device applications.(3)The result derivable from the equation show that the ratio of the strain over the magnetic field (△ε0/HAC) increased, the higher ME coefficient (αME) may be obtained. The result of the experiment show that he ratio of the hollow disk is five times larger than the rod and the αME of the close-looped sample is eight times larger than the solid disk. (4) According the sum property of the composite material and the radial vibration of a piezoelectric together with the Mason equivalent circuit model, the resonance frequency of the close-looped ME composite is available and the result of the calculated agrees well with the experimental result.(5) The electrical resistance load effects on close-looped ME laminated composite are studied and the change of the aME and the power output according the electrical resistance load are investigated. The result is helpful to design the practical device.(6) The ansoft-maxwell is used to simulation the effect of the narrow gap width on the magnetic phase. The magnetization of the material is decrease when the width of the gap increased because the demagnetization field is increase. The αME of the sample with narrow gap is larger than the close-looped one due to the boundary conditions change and this result is a good information for design the current transfer which is need replacement.