Research PVDF / Ceramic Powder Composite Thin Films And Dielectric Properties

PVDF, one of ferroelectric organic polymer materials, is currently the mostwidely used. As new functional composite materials, PVDF/ferroelectric ceramiccomposites not only overcome the defect of polymeric materials and theferroelectric ceramics, but also improve a part of electrical properties of thecomposites. They have the advantages of low density, high flexibility and easyprocessing，so they have potential application prospects in military, medical andelectronics industries and other fields. With the development of science andtechnology, we demand the PVDF/ceramic composites possess better performance.Therefore, it is important to improve the combination property of the composites.In this paper, PVDF is used as matrix, BaBi₄Ti₄O₁₅（BBiT）, La modifiedBaBi₄Ti₄O₁₅（BBiLT）, BaBi₂Nb₂O₉（BBN） and SrBi₂Nb₂O₉（SBN） are used as fillingcomposition, the PVDF/BBiT, BBiLT, BBN and SBN composites are prepared bysolution casting method. The main researches contain the change of dielectricproperty of PVDF/ceramic composites as the change of the contents and thepreparation methods of ceramics, film thickness and measuring frequency, and itsmechanism is discussed. The morphologies and the physical properties of thecomposites are characterized by scanning electron microscope, x-ray diffraction,fourier transform infrared spectro-metry, x-ray photoelectron spectroscopy andatomic force micro-scope. The micro-structure of ceramic powders and compositesare discussed.This experiment is used to explore the effects of composites’macro-performance and microscopic structure through changing the contents andvariety of ceramic, film thickness and measuring frequency. The experimental resultsshowed that the composite films with4%ceramic powders had better compactness,less internal defects, a higher relative amount of the β phase and better dielectricproperties. The dielectric properties of PVDF/SBN composite films were best amongthe composites, The highest dielectric constant was22.5and the least dielectric lossvalue was0.0255at the mass fraction of4%SBN. With the increasing thickness of the composite films, the dielectric constant and the dielectric loss increaseed, so thethickness should not be too large. The dielectric constant decreased and thedielectric loss increased as the measurement frequency. So measurement frequencyis as low as possible.