| In the present study,the melting recrystallization behavior of polyvinylidene fluoride(PVDF)were studied by transmission electron microscope(TEM)and fourier transform infrared spectroscopy(FTIR).And demonstrate all-polymer ferroelectric capacitor memory device in a structure of metal-ferroelectric polymer-metal by using highly oriented PVDF film.It was found that carbon-coated PVDF film exhibited highly orientation after melt-recrystallization process.In contrast PVDF film without carbon film exhibited disorder structure after same process.It is due to the existence of vacuum evaporated carbon film and as a result the molecular chain on the surface of the film was fixed.Vacuum evaporate carbon film stop the orientation in the surface from relaxation.In the isothermal crystallization process in 160 ℃,the sample fixed by vacuum evaporated carbon film grew into α form edge-on lamellae,while sample without carbon film grew into flat-on γ form lamellae.When using γ form flat-on lamellae as raw material,we can get flat-on y form lamellae as well.Taking advantage of the properties mentioned above,use highly oriented edge-on lamellae PVDF film as raw material,we get edge-ony form lamellae for the first time.This procedure is a combined action of high temperature crystallization and orientation fixing.By adjusting the stretching temperature and stretching rate,we got highly oriented PVDF film with extensive β form concentration.The c-axis of edge-on β form parallel to stretching direction with a-axis and b-axis rotate around it.Fabricating ferroelectric capacitor by one-step method and testing its properties.The PVDF ferroelectric device show excellent performance with a maximum remnant polarization～7.3μC/cm2,low coercive fields(150Mv/m),low leakage and good fatigue performance. |
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