The Study On The Preparation And Dielectric Property Characterization Of Two-dimensional Nanostructures Calcium Niobate

Dielectric energy storage devices are one of the important devices in power and electronic systems.The urgent demand for the miniaturization,implantation and high energy has stimulated the research on exploration of ultra-thin dielectric materials,especially two-dimensional(2D)nanosheets lamellar media.The results show that the2D niobate-based perovskite oxide nanosheets are homogeneous single crystal sheet with complete crystal structure and low defect concentration.Meanwhile,the 2D perovskite oxide nanosheets have 4d electrons in the outer layer of Nb⁵⁺ions,forming a niobium-oxygen octahedron with a large dipole moment,showing excellent stability and high dielectric properties,which is expected to become a core member of the molecular dielectric material system.The research on the 2D niobate-based perovskite oxide nanosheets energy storage medium is still mainly focused on the preparation and performance characterization,lacking of systematic research results and in-depth exploration on obtaining better performance materials through different preparation techniques.It is systematically studied the preparation of calcium niobate precursor powder and 2D nanosheet of monodisperse system,based on 2D nanosheet of thin film and SPS sintering ceramic medium,the dielectric properties of the molecule-level thin film medium and ceramic medium constructed by nanostructure were characterized and analyzed in deeply.Firstly,the influence of the preparation process of monolayer nanosheet on the morphology,size and dimension of the material was studied by bulk phase KCa₂Nb₃O₁₀ layered perovskite as the object.Results have shown that high purity and strong uniformity of nanosheet can be obtained by ultrasonic treatment,after the secondary stripping of the nanosheet dispersion centrifugal precipitate,the size of the single layer nanosheet is 5?m.Secondly,the dispersive supernatant and its centrifugal precipitates were treated by LB deposition technology and SPS sintering technology respectively to study the dielectric behavior of calcium niobate nanostructure with different thickness.On the one hand,the film formation process of monolayer calcium niobate nanosheet was investigated via LB deposition technology;the dielectric constant of calcium niobate film was analyzed with constructing the van der Waals homogeneous junction.The dielectric constant of calcium niobate at the molecular level was found to be between 200 and 250 by testing different layer films.On the other hand,through SPS sintering technology,the ceramic medium constructed by bulk phase and nanostructure calcium niobate was tested and analyzed,which showed that the ceramic medium constructed by nanostructure had higher dielectric constant and lower dielectric loss,the dielectric constant of calcium niobate ceramics can be increased to 1300.Combining with different preparation methods,the dielectric properties of 2D calcium niobate in constructing dielectric materials of different dimensions were investigated,the intrinsic dielectric values of molecular films were explored and the dielectric constants of ceramic dielectric were improved,and the potential application of 2D calcium niobate in energy storage devices was prospected.