Preparation And Dielectric Properties Of Conductive Nanoparticles-Deposited Barium Titanate/Poly (Vinylidene Fluoride) Composites

Owing to the rapid developments in science and technology,the dielectric materials with extraordinary performance were extremely demanded in the electronic system fields.Dielectric materials that possess high dielectric permittivity and dielectric field strength without excessive dielectric loss are necessary to meet the miniaturization requirements of microelectronic device-structures,including gate dielectrics,high charge-storage capacitors and electro-active materials.In this work,the dielectric properties of the composites are controlled by the surface structure design of inorganic filler particles,and the intrinsic relationship between the dielectric properties of the hybrid particles and the composites has been thoroughly studied experimentally and theoretically.The main research contents and results of the study are as follows:The Ni nanoparticles were coated on the surface of BT particles by electroless plating method and than the BT-Ni/PVDF composites were also prepared using hot press methods.The effects of BT-Ni particle on dielectric properties of the composites were studied.The increased conductivity of the interlayer between the BT and PVDF matrix created by the Ni nanoparticles enhances the space charge polarization and Maxwell–Wagner–Sillars effect.A high dielectric permittivity of the composites increased to 61 at 100 Hz when the content of BT-Ni filler was 20 vol.%,which is 2.58 times higher than that of 20 vol.% BT/PVDF.The Ni nanoparticles was strong interaction deposited on BT particles,and this structure can effectively suppress the probability of the Ni nanoparticles to form a conductive networks in the PVDF polymer matrix,which can greatly depress the increase of dielectric loss tangent and conductivity of the BT-Ni/PVDF composites.The BT-Fe₃O₄ hybrid particles were prepared using chemical precipitation method,on this basis,the sandwich structured BT-Fe₃O₄/PVDF composites were also prepared using solution casting and hot press methods.The dielectric constant of the composites can be significantly improved by incorporating Fe₃O₄ conductive particles into the polymer matrix.However,the Fe₃O₄ nanoparticles possess better conductivity can produce electrical current under an electrical field,resulting in high dielectric loss tangent and conductivity.The dielectric constant was slightly decreased with the center PVDF layer addition,but the conductivity as well as the dielectric loss of the composites was significantly reduced.The interface activation aE was calculated and shows that conductive Fe₃O₄ nanoparticles can increase the number of activated electrons at the interface between Fe₃O₄ and the PVDF matrix,which can significantly enhance the interface polarization and dielectric response under the electric field.Meanwhile,the capacity of the electric charges pass through the whole composites was restricted with the center PVDF layer addition,which decreases the dielectric loss of the composites.Moreover,the energy density of the 5vol.% BT-Fe₃O₄/PVDF-S composites are 2.24J/cm3 at 2100 k V/cm,and the efficiency also kept at 61%.