Pore architecture engineering to modulate piezoelectric energy harvesting performance of freeze-casted porous BCZT ceramics

Porous (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) piezoelectric ceramics have attracted considerable interests as promising materials for energy harvesting applications due to their controllably porosity, excellent piezoelectric coefficient (d₃₃), and outstanding figures of merit (FOM). This work first employed the freeze-casting method to prepare 3-1-type porous BCZT ceramics. Subsequently, polymethyl methacrylate (PMMA) was introduced as pore-forming agent for secondary pore formation, ultimately yielding 3-1-0-type porous BCZT ceramics. The influence of pore structure on the energy harvesting performance of porous BCZT ceramics was systematically investigated. Although d₃₃ linearly decreased from 413 pC/N to 125 pC/N with increasing PMMA content from 0 wt% to 0.5 wt%, the voltage coefficient (g₃₃) and FOM₃₃ were significantly enhanced, reaching peak values of 2017 × 10−3 Vm/N and 488 pm2/N, respectively. These findings elucidate microstructure-property relationships in porous piezoelectric materials and propose new design strategies for high-performance energy harvesters.