The Preparation Of Dendritic Barium Titanate Powders And Application Research

Firstly,the dendritic barium titanate(d-BT)powders were prepared.In addition,d-BT was used as the inorganic phase,and they were combined with PVDF and P(VDF-TrFE)organic phases to form d-BT/PVDF and d-BT/P(VDF-TrFE)composites respectively.The relation between the dielectric properties and the inorganic phase morphology of the composites were studied.Further optimize the dielectric properties of d-BT/P(VDF-TrFE)composites.With the properties of the dielectric constant of Al2O3 and TiO2 between d-BT and P(VDF-TrFE),the semiconductors Al2O3 and TiO2 were coated on the surface of d-BT,respectively.And the dielectric properties and energy densities of core-shell d-BT/P(VDF-TrFE)composites were studied.By comparing the reaction conditions,the suitable process conditions for the preparation of d-BT powder by hydrothermal method were obtained.The Ti(SO4)2 were chosen as titanium materials,The KOH concentration was 0.3 mol/L.When the reaction time was 6 h,10 h,12 h and 15 h,the four types d-BT powders were obtained,which were counted as 6h-d-BT,10h-d-BT,12h-d-BT and 15h-d-BT,respectively.And the dielectric properties of the four type composites 6h-d-BT/PVDF,1 0h-d-BT/PVDF,12h-d-BT/PVDF and 15h-d-BT/PVDF were studied and found that The dielectric properties of the 12h-d-BT/PVDF composites are optimal,and it is also significantly better than that of the spherical BaTiO3/PVDF composites,its breakdown strength is 306 kV/mm,the dielectric constant at 1 kHz is 15.04,and the energy density reaches 6.3 J/cm3.Therefore,12h-d-BT can be used as the better dendritic powders.The specific dimensions are that the trunk diameter and length are about 100-150 nm and 1.0-1.5 ?m,respectively,and the diameter and length of the small branch on the main trunk are about 100-150 nm and 150-250 nm,respectively.Through the investigation of the composites forming process,it was found that the uniformity of the temperature field affects the dielectric properties of the composites,and the dielectric properties of the composites under the uniform temperature field are superior.The dielectric properties of 12h-d-BT/P(VDF-TrFE)composites with the content of barium titanate of 0 vol%,1 vol%,3 vol%,5 vol%,and 7 vol%were studied and their energy density was calculated.The result shows that the maximum energy density of the 5 vol%12h-d-BT/P(VDF-TrFE)composite reaches 9.7 J/cm3,so the optimum d-BT content is determined to be 5 vol%.The charge energy density measured by hysteresis loop was 10.23 J/cm3,the discharge energy density was 5.44 J/cm3,and the discharge efficiency was 53.2%,which was more than twice that of pure P(VDF-TrFE).By the sol-gel method,Al2O3 and TiO2 were uniformly coated on the surface of the 12h-d-BT powder at pH=4.6 to obtain and the core-shell structures d-BT@Al2O3 and d-BT@Tiv2 powders.Among them,the 5 nm Al2O3 layer coated in the d-BT surface,and the TiO2 particles with 20 nm are uniformly grown on the d-BT surface.The dielectric properties of d-BT@Al2O3/P(VDF-TrFE)and d-BT@TiO2/P(VDF-TrFE)composites were studied,and The energy densities of d-BT@Al2O3/P(VDF-TrFE)and d-BT@Ti02/P(VDF-TrFE)materials were 11.62 J/cm3 and 12.83 J/cm3,respectively,which was 16.5%and 32.3%higher than that of d-BT/P(VDF-TrFE).