Enhanced breakdown strength of BaTiO_(3)-based multilayer ceramic capacitor by structural optimization

0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance variation limit)at 1 kHZ.The distribution of internal electric field under breakdown voltage was simulated by finite element method(FEM),indicating that the electric field strength increased significantly at the terminal of internal electrode.These areas may become the headstream of breakdown for MLCC-1 due to the shape mutation.In order to improve the breakdown performance of MLCC-1,it was optimized by 12BA5N+2G green sheets(prepared by 12BA5N ceramic powder with 2 wt%B-Al-Si glass additive),then MLCC-2 was obtained which satisfied EIA X8R specification.Its BDS rose from 20 to29.4 kV·mm^(-1),and the electric field distribution of dielectric layer was also analyzed by FEM.Besides,it was also found that the grain size and the dielectric constants of"core"and"shell"parts for the 12BA5N+2G dielectric layer both contributed to the enhanced BDS of MLCC-2according to the simulation results from FEM.