Strategic optimization of DC bias stability in BaTiO₃ ceramics through defect-engineered core-shell architectures

BaTiO₃-based multilayer ceramic capacitors (MLCCs) with Ni inner electrodes face two critical challenges: DC bias causes a sharp decrease in the dielectric constant, and the material may become semiconducting during sintering in a reducing atmosphere. To overcome these issues, we adopted a multi-element (Y, Mn, Mg) doping strategy to successfully construct a core-shell architecture. This design significantly suppresses the decay of the dielectric constant in the core under a DC bias. A systematic analysis was conducted on the effects of sintering atmosphere and annealing on the microstructure and dielectric properties. The results reveal that the sample Y-N, sintered in a reducing atmosphere, exhibits excellent DC bias stability. This can be attributed to its higher defect concentration, which effectively inhibits the migration of oxygen vacancies. Consequently, Y-N shows only a −0.61% decay rate of the dielectric constant at 2 V/μm, while achieving remarkable temperature stability (meeting the EIA X8R specification) and frequency stability (with a −2.1% variation from 1 kHz to 1 MHz). In contrast, samples annealed in air exhibit degraded DC bias stability at high electric fields due to shell thinning. This work provides valuable insights for the development of highly reliable dielectric materials for base-metal electrode MLCCs applications.