Preparation Of Alien-shaped Barium Titanate And Application Research In Composite

In order to improve the dielectric properties of organic-inorganic dielectric composites,a coral-shaped barium titanate(c-BaTi03,c-BT)powders were synthesized and the c-BT/PVDF composites are prepared by solution casting,in which the organic acids with catechol-based were used as modifiers.The dielectric properties of c-BT/PVDF composites were studied and the improving mechanism of the dielectric properties was gaven.c-BT particles are prepared by a hydrothermal method,in which,CTAB as a template agent.The effects of reaction time,reaction temperature and Ba/Ti ratio on c-BT particle morphology were studied.When Ba/Ti=1.014,reaction temperature and time are 180℃ and 12 h,respectively,the c-BT particles as synthesized were good crystallinity and uniform size..The particle size can be expressed as,total length and width were about 600～1000 nm and 150-150nm,respectively,each monomer coral about 100～200 nm long and 60～100nm in diameter.Comparison of different components in electrical performance of c-BT/PVDF composites,7vol%c-BT/PVDF composite dielectric constant is 12.5 at 1 kHz and the breakdown strength is 297.2kV·mm-1,then the energy storage density reach to 4.84 J·cm-3.When select catechol organic acid as modifier,the dielectric constant of CA@c-BT/PVDF,DHBA@c-BT/PVDF,DHPA@c-BT/PVDF,DHCA@c-BT/PVDF composites are 17.3,16.7,15.9 and 15.2,respectively.The breakdown field strength of composites are all greater than 250 kV·mm-1,especially CA,the CA@c-BT/PVDF composites breakdown voltage is 300.5kV·mm-1 and energy density is 6.92 J·cm3,this is 2 times than the density of pure PVDF and 1.5 times than untreated c-BT/PVDF composites.The reason analysis of the better dielectric properties of c-BT/PVDF composites can be attributed to the addition of c-BT powders and the use of modifiers,as well as interfacial polarization and matrix phase transformation.(1)the branched c-BT particles in the material provide a significant contribution to the compressive strength of the composites;(2)the interfacial differences between the c-BT particles and PVDF organic phase can be used to provide the dielectric performance;(3)with the introduction of branched particles,the phase can be induced to change in composite,so that the β and γphase contents of the composite material can be improved;(4)the functional groups such as benzene ring,carboxyl group,hydroxyl group and double bond contained in catechol phenolic can enhance the electronic effect and polarization in the composite,result in the improvement of the dielectric properties of the c-BT/PVDF composite.