Improved energy-harvesting performance of (K, Na)NbO3-based ceramics through the synergistic effect of texture and defect engineering

Textured CuO-doped KNN-based ceramics with [001]_C orientation were developed to enhance energy harvesting performance. Textured ceramics doped with 0.3 mol% CuO exhibit remarkable piezoelectric coefficients d₃₃ of 347 pC/N and g₃₃ of 96 × 10⁻³ Vm/N, resulting in a higher figure of merit (d₃₃ × g₃₃ ∼ 33 × 10⁻¹² m²/N) for evaluating energy conversion. The d₃₃ and g₃₃ increased by 105 % and 269 %, respectively, compared to those of randomly oriented ceramics. The piezoelectric energy harvester fabricated using the textured ceramic achieved an output power density of 3 μW/mm³, comparable to PZT-based energy harvesters. The enhancement in d₃₃ is mainly due to favorable [00 l]_C orientation. The orientation, along with the hardening effect caused by CuO doping, contributes to decreased dielectric coefficient ε^T_r3, resulting in increased g₃₃. The synergistic strategy is expected to facilitate the design high-performing, eco-friendly piezoelectric ceramics.