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

Area of Science:

• Materials Science
• Solid State Chemistry
• Computational Materials Science

Background:

• Oxygen vacancies (V_Os) significantly degrade the insulation reliability of barium titanate (BaTiO₃)-based multilayer ceramic capacitors (MLCCs).
• Understanding the atomic-scale mechanisms of V_O stabilization is crucial for improving MLCC performance.

Purpose of the Study:

• To investigate the effect of B-site doping with cerium (Ce) on V_O stabilization in BaTiO₃.
• To elucidate the mechanisms of V_O stabilization by Ce and co-dopants (Er, Mn).
• To develop a predictive descriptor for electron trapping sites.

Main Methods:

• Density functional theory (DFT) calculations were employed to model defect interactions and electronic structures.
• Analysis of electron trapping and ionic radius changes associated with Ce doping.
• Investigation of co-doping effects (Ce-Er, Ce-Mn) on V_O stabilization.

Main Results:

• Ce doping at the Ti-site (Ce_Ti) strongly stabilizes V_Os by trapping electrons and increasing local ionic radius, suppressing V_O migration.
• Ce-Er co-doping effectively traps V_Os, while Ce-Mn co-doping shows slightly lower stabilization due to preferential Mn trapping.
• A descriptor based on trap-state characteristics was proposed to predict preferred electron trapping sites.

Conclusions:

• Ce doping is a promising strategy for enhancing the insulation reliability of BaTiO₃-based MLCCs.
• The findings provide atomic-scale insights into defect stabilization mechanisms.
• The developed descriptor can guide the rational design of additives for improved MLCC performance.