Piezoelectric Ceramics for Use in Multilayer Actuators and Energy Harvesters

Microstructural and piezoelectric properties of 0.72Pb(Zr_1?xTi_x)–0.28Pb(Zn_0.4Ni_0.6)_1/3Nb_2/3O₃ (PZ_1?xT_x‐PZNN) ceramics with 0.50 ≤  x ≤ 0.55 were investigated for evaluating the possibility of their use in multilayer actuators and energy harvesters, which demand a large piezoelectric strain constant (d₃₃) and a small dielectric constant (ε^T₃₃/ε_o). The PZ_0.47T_0.53‐PZNN ceramic with a morphotropic phase boundary (MPB) composition showed large d₃₃ and ε^T₃₃/ε_o values, making it unsuitable for use in multilayer actuators and energy harvesters. However, the PZ_0.48T_0.52‐PZNN ceramic with a rhombohedral structure showed a small ε^T₃₃/ε_o value of 1605, yet maintained a large d₃₃ of 550 pC/N. Thermal stimulation did not have any significant effect on the piezoelectric properties of this specimen, except for a slight increase in the ε^T₃₃/ε_o value upon heating the specimen at 150°C for 4 h. In an effort to reduce the sintering temperature, CuO was used as an additive for the ceramic. As a result, the CuO‐added PZ_0.48T_0.52‐PZNN ceramic was well sintered at 900°C. In particular, the 1.0 mol% CuO‐added PZ_0.48T_0.52‐PZNN ceramic exhibited a large d₃₃ value of 554 pC/N and a small ε^T₃₃/ε_o value of 1620, making it highly suitable for use in multilayer actuators and energy harvesters.