Lower-temperature sintered high energy density fine-grained sodium bismuth titanate - strontium bismuth titanate ceramics multilayer capacitors

The breakdown field strongly determines the energy density of energy-storage ceramic capacitors. In this work, a compound sintering aid of CuO and SiO₂ was preferably selected to explore the effect on sintering behavior and energy storage of sodium bismuth titanate - strontium bismuth titanate (NBT-SBT) relaxor ferroelectrics. The optimum sintering temperature promotes a dense microstructure and fined-grain size in NBT-SBT, which contributes to an increase in breakdown strength. Meanwhile, the appropriate CuO/SiO₂ ratio retains the advantages of the high polarization value of NBT-SBT. Specifically, when sintered at 1040 °C with 0.2 wt% SiO₂ and 0.8 wt% CuO composite sintering aids, the NBT-SBT bulk ceramics achieved an energy storage density of 4.09 J/cm³ under a high electric field of 270 kV/cm. Owing to the lower sintering temperature, the NBT-SBT achieved co-firing with 30/70 Ag/Pd electrodes. Finally, multilayer ceramic capacitors with a recoverable energy density of 8.43 J/cm³ have been successfully fabricated.