Synergistic enhancement of dielectric properties and reliability of BaTiO₃-based MLCC via compositional gradient design and nano-domain engineering

Dielectrics with high dielectric constant, low dielectric loss, and good temperature stability are essential for BaTiO₃-based MLCCs to meet the escalating demands of 5G communication technologies. However, challenges remain in further optimizing dielectric properties due to the correlation between these parameters. This study proposes a synergistic design strategy that overcomes this limitation through the coupling of compositional gradient control and nano-domain engineering. An optimized 900 ℃ pre-sintering process enables precise structural regulation, forming a tetragonal barium titanate core surrounded by a dopant-enriched graded compositional-gradient shell structure. Atomic-scale analysis confirms that the gradient design achieves directional distribution of Y/Mg/Mn dopants, stabilizes the highly tetragonal core, and confines oxygen vacancy-related defects to the shell region. This defect-localization effect suppresses long-range vacancy migration, thereby significantly enhancing insulation resistance and breakdown strength. Concurrently, the formation of relaxor-like polar nanodomains not only contributes to high dielectric constant but also optimizes the temperature stability of dielectric constant. Ultimately, the prepared ceramic materials exhibit a high dielectric constant (ε_r > 2200), excellent thermal stability meeting X8R standards (−55–150 ℃, ΔC/C_25℃ ≤ ±15%), and enhanced breakdown strength (> 6.7 kV/mm). This finding implies that the synergistic regulation of compositional gradients and nano-domain engineering may be a promising strategy for designing both high capacitance and robust reliability dielectric materials and provides a broad opportunity for the development of other dielectric materials.