Preparation And Properties Of NBT-based Ceramics/PVDF Composite Films

With the development of modern science and technology,the field of power electronic systems urgently needs more excellent dielectric materials.Among them,Microelectronic devices such as gate dielectrics,high-density capacitors,and electroactive materials all require nanocomposites to have a high dielectric constant,low dielectric loss,high breakdown field strength,and good toughness.Traditional polymer materials have the characteristics of small volume,easy processing and low permittivity,which are difficult to meet the requirements of practical use.The use of composite methods to improve the energy storage characteristics of traditional polymer materials has become a hot topic at the moment.Therefore,in order to improve the energy storage characteristics of the composite film,the subject chose poly(vinylidene fluoride)(PVDF)as the matrix and Na0.5Ti0.5TiO3-based ceramics as the fillers,through a series of design of ceramic powder formulation,morphology and film composite structure,the PVDF composite film was doped and modified,and its related properties were studied in detail.0.5SrTiO3-0.5(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)(SBNBT)ceramic powders were prepared by the traditional solid-phase method,then a single-layer zero-dimensional SBNBT/PVDF composite film was prepared by the solution blend casting method.The research results show that ST,NBT and BT can form perfect perovskite solid solution.As the amount of SBNBT ceramics in the composite film increases,the permittivity(?r)of the sample gradually increases,and the dielectric loss(tan?)decreases first and then increases.When the volume ratio of ceramic is 6 vol%,the sample get the best energy storage characteristics.At this time,the maximum breakdown electric field(Emax)is 325 MV·m-1,the effective energy storage density(Ue)is 6.53 J·cm-3,and the energy storage efficiency(?)is 68%.One-dimensional 0.26SrTiO3-0.74Na0.5Bi0.5TiO3(SNBT)ceramic whiskers were prepared by the molten salt method,then a single-layer one-dimensional SNBT/PVDF composite film was prepared by the solution blend casting method.The results show that the prepared SNBT whiskers have pure perovskite structure.With the increase of SNBT whisker content in the composite film,the ?r and the tan? of the sample increase simultaneously.When the whisker content is 2 vol%,the sample get the best energy storage characteristics.At this time,Emax=320 MV·m-1,Ue=5.3 J·cm-3,and/?=64.14%.Two-dimensional Na0.5Bi0.5TiO3(NBT)ceramic platelets were prepared by the molten salt method,then a two-layer two-dimensional NBT/PVDF composite film was prepared by twice solution blend casting methods.The results show that the prepared NBT platelets have pure perovskite structure.With the increase of the NBT platelets content in the composite film,the ?r and the tan? of the sample increase simultaneously.When the amount of the ceramic platelets in the composite layer is 5 vol%,the sample get the best energy storage characteristics.At this time,Emax=650 MV·m-1,Ue=22.6 J·cm-3,and ?=80.26%.One-dimensional Na0.5Bi0.5TiO3(NBT)ceramic whiskers were prepared by the molten salt method,then a sandwich-structure one-dimensional NBT/PVDF composite film was prepared by three-time solution blend casting methods.The results show that the prepared NBT whiskers have a pure perovskite structure.With the increase of NBT whisker content in the composite film,the ?r of the sample gradually increased,and the tan? decreased first and then increased.When the amount of ceramic whiskers in the inner layer is 6 vol%,the sample get the best energy storage characteristics.At this time,Emax=615 MV·m-1,Ue=30.55 J·cm-3,?=80.2%.One-dimensional 0.15SrTiO3-0.85Na0.5Bi0.5TiO3(SNBT)ceramic whiskers were prepared by the molten salt method,then a five-layer structured one-dimensional SNBT/PVDF composite film was prepared by five-time solution blend casting methods.The results show that the prepared SNBT whiskers have a pure perovskite structure.With the increase of SNBT whiskers content in the composite film,the ?r of the sample gradually increased,and the tan? decreased first and then increased.When the amount of ceramic whiskers in the second-outer layer is 6 vol%,the sample get the best energy storage characteristics.At this time,Emax=640 MV·m-1,Ue=20.82 J·cm-3,and ?=64.28%.