Enhanced piezoelectricity of [001]-textured (K,Na)(Nb,Sb)O3–(Bi,Ag)ZrO3 ceramics using Na(Nb0.9Sb0.1)O3 templates at low temperature

Abstract

In this study, 2.0 mol% CuO-added 0.96(K_0.5Na_0.5)(Nb_1−zSb_z)O₃–0.04(Bi_0.5Ag_0.5)ZrO₃ [CKN(N_1−zS_z)–BAZ] piezoceramics (0.0 ≤ z ≤ 0.08) were densified at 980 °C without the secondary phase. The crystal structure of the CKN(N_1−zS_z)–BAZ piezoceramics changed from the tetragonal–orthorhombic structure to the tetragonal–orthorhombic–pseudocubic structure with increasing z. The CKN(N_1−zS_z)–BAZ piezoceramics (0.0 ≤ z ≤ 0.07) were well textured at 980 °C along the [001] direction, without holes, when 3.0 mol% Na(Nb_0.9Sb_0.1)O₃ (NNS) templates were used. However, the specimens textured using NaNbO₃ (NN) templates exhibited holes owing to the dissolution of the NN templates. Moreover, the elastic modulus and hardness of the specimen (z = 0.05) textured using the NNS template were larger than those of the specimen (z = 0.05) textured using the NN template, possibly because of the absence of holes. The [001]-textured CKN(N_1−zS_z)–BAZ piezoceramics exhibited a reduced dielectric constant and enhanced piezoelectric properties. Particularly, the [001]-textured CKN(N_0.95S_0.05)–BAZ piezoceramic provides large d₃₃ (610 pC N⁻¹), k_p (0.68) and d₃₃ × g₃₃ (30 × 10⁻¹² m² N⁻¹) values. A cantilever-shaped piezoelectric energy harvester was fabricated using the [001]-textured CKN(N_0.95S_0.05)–BAZ ceramic, which showed a large output power of 1.6 mW at the resonance frequency, indicating that this piezoceramic is a good candidate for a piezoelectric energy harvester.