DFT-guided additive design for BaTiO₃-based MLCCs exhibiting excellent insulation reliability

Oxygen vacancies (V_Os) degrade the insulation reliability of BaTiO₃-based multilayer ceramic capacitors (MLCCs). Density functional theory calculations reveal that Ce doped at the B-sites (Ce_Ti) of BaTiO₃ strongly stabilizes V_Os, effectively suppressing V_O migration. This stabilization originates from electron trapping by Ce_Ti, which reduces Ce⁴⁺ to Ce³⁺ and substantially increases the involved ionic radius. The resulting size mismatch reduces the stability of Ce_Ti, enabling strong interaction with adjacent V_Os. In co-doped BaTiO₃, Ce-Er combination effectively traps V_Os by promoting electron trapping at Ce. Meanwhile, Ce-Mn co-doping leads to preferential electron trapping by Mn, resulting in slightly lower V_O stabilization. To explain variations in electron trapping, we propose a descriptor based on trap-state characteristics, enabling prediction of the preferred trapping site. Overall, these findings provide atomic-scale insights for designing additives that enhance the insulation reliability of MLCCs.