Regulating polar nanoregion dynamics for enhanced DC-bias stability and energy storage in relaxor ferroelectric ceramics

Dielectric materials for multilayer ceramic capacitors must maintain stable permittivity under high electric fields, yet conventional systems often suffer from DC-bias-induced degradation due to coupling between polarization response and field-induced saturation. Here, we report a relaxor engineering strategy in (1 − x )[0.7(Na 0.4 K 0.1 Bi 0.5 )TiO 3 -0.3(Sr 0.2 Bi 0.7 )TiO 3 ]– x CaSnO 3 ceramics to mitigate the trade-off between dielectric permittivity and DC-bias stability. The incorporation of CaSnO 3 , which acts as a non-ferroelectric component with negligible intrinsic polarization contribution, induces lattice distortion and compositional heterogeneity. These structural perturbations suppress the dielectric peak and restrain long-range ferroelectric ordering, thereby improving the bias stability of ceramics. Consequently, the ceramics exhibit typical relaxor behavior with slim polarization–electric-field loops, low remanent polarization, and thermally robust polarization characteristics. Most importantly, DC-bias stability is markedly improved, where the dielectric variation under ±40 kV/cm decreases from over 30% to within ±5.2% with increasing CaSnO 3 content, while retaining relatively high permittivity. This behavior is attributed to the suppression of polar nanoregions by CaSnO 3 incorporation, which reduces dielectric peak intensity and field sensitivity while improving bias stability. These results suggest that compositional suppression of polar nanoregion activity is an effective strategy for developing high-reliability dielectric materials.