Piezoelectricity of (K,Na)(Nb,Sb)O-3-SrZrO3(Bi,Ag)ZrO3 piezoceramics and their application in planar-type actuators

Abstract

A Fe2O3-added 0.96(K0.5Na0.5)(Nb0.94Sb0.06)-0.01SrZrO(3)-0.03(BiAg)ZrO3 [KNNS-0.01SZ-0.03BAZ] piezoceramic was well densified at 1090 degrees C. It exhibited a large piezoelectric charge constant (d(33)) of 650 pC/N, which is close to the largest d(33) value reported in the literature. This sample has a tetragonal-orthorhombic-rhombohedral (T-O-R) structure, in which each structure has a similar proportion. Moreover, nanodomains (2 nm x 15 nm) with a low domain boundary energy were found in this sample, which exhibited relaxor properties. Therefore, the presence of a T-O-R multi-structure and nanodomains is responsible for the large d(33) value of this sample. A KNNS-0.01SZ-0.03BAZ thick film was synthesized, and it also had a T-O-R multi-structure with a large d(33) (630 pC/N). A planar-type actuator was produced using this thick film, and this actuator exhibited large acceleration (335 G at 120 V mm(-1)) and displacement (231 mu m at 120 V mm(-1)). Hence, the KNNS-0.01SZ-0.03BAZ thick film is a good candidate for lead-free piezoelectric actuators.