Structure-reinforced periodic porous piezoceramics for ultrahigh electromechanical response manufactured by vat photopolymerization

Traditionally, it is accepted that the lower permittivity of porous piezoceramics contributes to a high piezoelectric voltage coefficient(g₃₃). However, this enhancement is not evident due to the insufficient polarization and inefficient stress transfer in porous piezoceramics with random and irregular pores. Herein, Gyroid structures with triply periodic minimum surface lattices are introduced into the fabrication of porous piezoceramics by vat photopolymerization technology. Based on experimental and simulation data, porous piezoceramics need to be subjected to higher electric fields (5 kV/mm) to achieve a fuller polarization, whereas the Gyroid structure has stable and excellent resistance to electrical breakdowns. Meanwhile, the increase in the average stress and the effective stress transfer in the Gyroid structure offset the negative effect of the decrease in the piezo-phase on the piezoelectric properties. Ultimately, d₃₃ remained unexpectedly stable and are essentially the same value as in the bulk ceramics during the increase in porosity from 55 vol.% to 75 vol.%. Expectedly, due to the significant reduction of the dielectric constant, an ultrahigh g₃₃ value up to 89 mV∙m/N is achieving in 75 vol.% porosity porous ceramics, more than 3 times that of bulk ceramics. Moreover, the Gyroid structure also has excellent compressive strength. Therefore, this work highlights the great potential of 3D printing technology in developing microarchitecture piezoceramics with ultrahigh electromechanical response.