Composite Nanoarchitectonics of TiO ₂ /SiO ₂ ‐Loaded Rare‐Earth Metal Coordinated Prussian Blue Analog Composites for Enhanced Electroresponsive Performance

Electrorheological fluids (ERFs) represent a novel class of electric field–responsive materials capable of rapid fluid–solid phase transition. However, conventional TiO ₂ or SiO ₂ (TiO ₂ /SiO ₂ ) used as dispersed phases suffer from low yield stress and poor sedimentation stability, which limit engineering applications in impact‐resistant high‐end devices. This study designs a conductor–semiconductor composite material. The TiO ₂ /SiO ₂ ‐loaded rare‐earth metal coordinated Prussian blue analog (PBAs) composites (Eu/Ce‐Fe PBA@TiO ₂ /SiO ₂ ) are synthesized using the coprecipitation method as dispersed phases of ER. The influence of morphological characteristics, structural configuration, and coordination mode of the composites on ER performance was systematically investigated. Compared with Eu/Ce‐Fe PBA, the Eu/Ce‐Fe PBA@TiO ₂ composite demonstrates over a fivefold enhancement in dielectric properties, significantly improving polarization performance. This enhancement arises from constructed heterojunction interfaces that enable semiconductor–conductor synergistic effects, facilitating rapid electron transport and enhanced interfacial polarization. By comparing the ER activities of composites with different metal coordination, Eu/Ce‐Fe PBA@TiO ₂ /SiO ₂ ‐based ERFs exhibit the optimal performance. Notably, EuFe(CN) ₆ @TiO ₂ ‐based ER fluid achieves 2 months of sedimentation stability at room temperature and delivers a shear stress of 1200 Pa under an electric field of 3 kV mm ^–1 . This research provides a valuable reference for achieving ER performance improvement through material design and demonstrates promising engineering application potential.