High-sensitivity piezoelectric response enabled by heterogeneous stress–electric field distribution in 3D interconnected porous ceramics

Abstract Porous piezoceramics are attractive for high-sensitivity sensing and energy conversion due to their low density, reduced dielectric constant (εr), and good mechanical compliance. However, increasing porosity is often accompanied by a significant reduction in the piezoelectric charge coefficient (d33), creating an intrinsic trade-off that limits the practical use of porous structures in high-sensitivity piezoelectric devices and leaves their overall performance advantages under debate. In this work, we overcome this challenge by developing a fully open-cell, three-dimensionally interconnected Pb(Zr1/2Ti1/2)O3–Pb(Zn1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3 (PZT–PZN–PNN, PZNNT) porous piezoceramic (3D-PPC). Despite an ultrahigh porosity of 92%, the material maintains a high d33 of approximately 470 pC/N, approximately 90% of that of the dense ceramic. The effective εr is reduced to approximately 140 (a 94% decrease), leading to an approximately 14-fold enhancement in the piezoelectric voltage coefficient g33 (approximately 380×10−3 Vm/N). Combined microstructural characterization, domain analysis, defect studies, and multiphysics simulations show that the exceptional performance arises from synergistic effects of heterogeneous stress and electric fields, multiscale domain structures, and defect-mediated regulation within the three-dimensionally interconnected porous architecture. Finally, the material generates peak output voltages up to 200 V under subtle mechanical excitation and achieves an ultrahigh sensitivity of 38.7 V/kPa. These results show that three-dimensionally interconnected porous architectures are not merely passive means of reducing dielectric permittivity but also active structural strategies for tuning local fields and polarization behavior.