The Research On Preparation And Properties Of BaTiO₃-based Dielectric Energy Storage Film And Ceramics

Environmental pollution and energy crisis have become the main problems affecting social development.Therefore,every country is committed to the research and development of new energy.Dielectric capacitor have been used in the field of pulse power supply because of several advantages such as fast charge and discharge rate,high power density,safety and stability.Barium titanate(BaTiO₃)is environmentally friendly as a lead-free material with excellent dielectric and ferroelectric properties,which is widely used in electronic fields such as capacitors and thermistors.Due to the influence of phase transition and macroscopic electric domain,barium titanate ceramics still have some shortcomings in the field of dielectric energy storage.At present,it is urgent to improve its energy storage density and efficiency to meet the requirements of high integration and miniaturization of equipment.In this paper,barium titanate is converted from ferroelectric to relaxor ferroelectric by using different components of solid solution doping to improve energy storage density and energy storage efficiency.Barium titanate based dielectric energy storage films and ceramics were prepared by physical vapor deposition and solid-phase sintering respectively.The main research results are as follows:Explore the technology of preparing BaTiO₃-based thin films by vacuum electron beam evaporation,and prepare Ba_1-xBi_xTiO₃and(1-x)BaTiO₃-x BiniO₃thin films.By introducing other components into ABO₃,the long-range ordered structure of barium titanate is destroyed,and the macroscopic ferroelectric domain is transformed into a nanometer polarized region,which responds faster to the applied electric field,thus generating smaller hysteresis loops and improving the energy storage efficiency.The energy storage density of Ba_0.9Bi_0.1TiO₃and0.95BaTiO₃-0.05Bi NiO₃films reaches 12.04 J/cm³and 11.51 J/cm³,respectively,and the energy storage efficiency is 54.3%and 62.9%,respectively.Ba_1-x(Bi_1/2Sm_1/2)_xTiO₃ ceramics were prepared by solid-state sintering method,introducing Bi³⁺and Sm³⁺ions into BaTiO₃matrix.With the increase of x,the structure changes from tetragonal phase to pseudo-cubic phase,and Bi³⁺and Sm³⁺ions can completely enter the BaTiO₃structure to replace Ba²⁺ions at the A position.With the introduction of doping components,the breakdown electric field increases and the energy storage density increases.When x?0.16,the ceramics transform from ordinary ferroelectric to relaxor ferroelectric,with the increase of energy storage density,efficiency and frequency stability.When x=0.16,the energy storage density 0.173 J/cm³,and the energy storage efficiency is 92.1%.(1-x)BaTiO₃-xSrNb_0.5Al_0.5O₃ ceramics were prepared by solid-phase sintering,and Bi³⁺and Sm³⁺were introduced to prepare(1-x)Ba_0.84(Bi_1/2Sm_1/2)_0.16TiO₃-x Sr Nb_0.5Al_0.5O₃ceramics.With the increase of x,the crystal structure changes from cubic phase to pseudo-cubic phase,indicating that Sr³⁺and(Nb_0.5Al_0.5)³⁺enter the A and B sites of BaTiO₃,respectively.After the introduction of doping components,the interaction between the long-range dipoles is destroyed,thus the common ferroelectric material is transformed into a relaxed ferroelectric material.The hysteresis behavior of barium titanate can be ignored,the grain size decreases,the saturation polarization electric field increases significantly,and both the energy storage density and efficiency are improved.The energy storage efficiency of 0.95BaTiO₃-0.05Sr Nb_0.5Al_0.5O₃and0.95Ba_0.84(Bi_1/2Sm_1/2)_0.16TiO₃-0.05Sr Nb_0.5Al_0.5O₃ ceramics reaches 75.5% and 96.3%,respectively.