Breaking the Porosity‐Property Trade‐Off in Piezoceramics Via Self‐Assembled Pore Engineering

The practical applications of porous piezoelectric ceramics have long been constrained by the intrinsic trade‐off between porosity and their piezoelectric and mechanical properties. Existing pore‐forming techniques, such as burnt‐out polymer spheres, still fail to achieve synergistic optimization of these properties. Here, we propose a self‐assembled pore engineering (SAP), which utilizes the density difference between reactants and products during chemical reactions to enable spontaneous pore formation. Benefiting from the synergy of SAP‐induced lattice softening, domain refinement, and significant residual stress, the fabricated porous bismuth layer‐structured Ca 0.94 Bi 4.06 Ti 4 O 15 (Bi‐CBT) ceramics with 30% porosity exhibit excellent comprehensive performance. The piezoelectric coefficient d 33 reaches 23.1 pC/N and shows a variation within ±15% over a broad temperature range of 25°C–525°C, while simultaneously possessing excellent compressive strength (558 MPa at 25°C, 276 MPa at 600°C) and low thermal conductivity (0.57 W m−1 K−1 at 25°C). More importantly, this method demonstrates broad universality across different material systems. Porous perovskite‐structured BaTiO 3 prepared via SAP achieves an ultrahigh effective electrostrictive coefficient Q eff of 0.32 m 4 /C 2 . These findings establish a versatile, low‐cost route for the scalable production of structural‐functional integrated ceramics.