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 PZT-PZN-PNN porous piezoceramic (3D-PPC). Despite an ultrahigh porosity of 92%, the material maintains a high d33 of ~470 pC N⁻¹, about 90% of that of the dense ceramic. While its effective εr is reduced to ~140 (a 94% decrease), leading to an approximately 14-fold enhancement in the piezoelectric voltage constant g33 (~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 active structural strategies for tuning local fields and polarization behavior.
Feng et al. (Sun,) studied this question.