Multi-scale coherent interfaces in core–shell Sr_0.875La_0.1TiO₃-based textured ceramics for enhanced high temperature thermoelectric performance

SrTiO₃-based thermoelectric ceramics show potential for high-temperature energy harvesting but face challenges from inefficient carrier transport and high thermal conductivity. This work presents a multi-scale structural engineering strategy to address these challenges, fabricating textured Sr_0.875La_0.1TiO₃/nm Ti/10 wt% Bi₂O₃ (SLTTB) ceramics via plate-like SrTiO₃ templates. Through this design, the ceramics form a unique core–shell architecture, where template seeds act as growth cores for epitaxially aligned <100> oriented grains, forming coherent interfaces with a precipitate-rich interlayer and a precipitate-free shell. In the interlayer, uniformly distributed “peanut-shaped” Bi-Ti_nO_{2 n −1} nanoparticle pairs enhance electron mobility and phonon scattering. The hierarchical microstructure creates multi-scale coherent interfaces that reduce electron grain boundary scattering, enabling preferential electron transport pathways parallel to the casting direction. This architecture enables the decoupling of electrical and thermal properties, with a power factor reaching 1815 μW/m/K² at 1073 K with thermal conductivity suppressed by interfacial and nanoparticle scattering. Consequently, the SLTTB textured ceramic achieves a notable ZT of 0.64 at 1073 K, a significant enhancement over conventional counterparts. This work demonstrates a multi-scale structural strategy integrating template-induced texture, core–shell design, and nanoscale interface modulation to decouple the electrical and thermal properties of SrTiO₃-based materials, and provides a roadmap for tailoring the electrical-thermal transport properties of thermoelectric textured ceramics.