Preparation And Energy Storage Characteristics Of NBT Based Multilayer Ceramic Capacitor

As an indispensable passive component,multilayer ceramic capacitors（MLCCs）are widely used in various electronic devices.The performance of multilayer ceramic capacitors is mainly determined by the performance of the dielectric ceramic material.However,the current energy density of dielectric ceramics is relatively low,which limits their application in energy storage.For this reason,improving the energy storage performance of multilayer ceramic capacitors using ceramics as dielectric materials is the research purpose of this thesis.Ferroelectric ceramics are prepared by extension process,and their microstructure,dielectric response,energy storage performance and discharge performance are systematically studied,and the components with the best energy storage performance are prepared by screen printing,lamination and other processes.Multilayer ceramic capacitors have high energy storage density.First,(Na_0.5Bi_0.5TiO₃-Sr_0.7La_0.2TiO₃)ceramics are prepared in this thesis,the energy storage properties of the ceramics under different NBT/SLT ratios are studied,and a basic component is determined for the subsequent doping modification.Finally,it is found that the0.55Na_0.5Bi_0.5TiO₃-0.45Sr0.7La0.2TiO3 component ceramic has the best energy storage performance.Under the breakdown field strength of 220 k V/cm,the energy storage is 2.52 J/cm³,and the efficiency can reach 88%.Secondly,according to the actual experiment,it is found that the sintering process has a very significant impact on the energy storage of ceramics,so it is very meaningful to explore the sintering process of ceramics before the specific doping modification.Therefore,the ceramic composition of 0.55Na_0.5Bi_0.5TiO_3-0.45Sr_0.7La_0.2TiO₃ is selected in this thesis,and Bi(Mg_2/3Nb_1/3)O₃（BMN）is introduced.BMN can reduce the grain size and improve the breakdown field strength,0.85(0.55Na_0.5Bi_0.5TiO₃-0.45Sr_0.7La_0.2TiO₃)-0.15Bi(Mg_2/3Nb_1/3)O₃ceramics are prepared.The effect of sintering temperature on the structure,dielectric properties and ferroelectric properties of the ceramics is studied.The results show that the ceramics had the best energy storage performance of 3.88 J/cm³ and an efficiency of 85%at a suitable sintering temperature（1170℃）.The electric field can reach 348 k V/cm³.Finally,according to the above research,it is found that the ceramics doped with BMN components generally have low polarization,which is not conducive to obtaining high energy storage density,so the basic component of the ceramics is changed to 0.6Na_0.5Bi_0.5TiO₃-0.4Sr_0.7La_0.2TiO₃ with higher polarization composition.And because BMN doping will cause great changes in the breakdown field strength,the effect of BMN doping amount on the energy storage performance of ceramics is studied,and 1-x(0.6Na_0.5Bi_0.5TiO₃-0.4Sr_0.7La_0.2TiO₃)-x Bi(Mg_2/3Nb_1/3)O₃ceramics is prepared.Finally,under the optimal doping amount of BMN with x=0.12,the breakdown field strength can reach an excellent 509 k V/cm,the best energy storage density of 6.5 J/cm³ and efficiency of 85%are obtained,and the power density can reach 215MW/cm³.And then use this component to prepare a multilayer ceramic capacitor,and obtain extremely excellent energy storage performance,the breakdown field strength is very high 1135k V/cm,the releasable energy storage can reach a very high 15.6 J/cm³,and the efficiency can reach 89.9%.