Textured and Tungsten-bronze-niobate-doped (K,Na,Li)(Nb,Ta)O3 Piezoceramic Materials

In this study, the effects of an alkaline-earth niobate doping in tungsten-bronze (TB) stochiometry on the piezoelectric properties and the phase transition temperatures of lead-free (K,Na,Li)(Nb,Ta)O-3 ceramics were investigated. In particular, the TB compounds barium niobate (BN), barium sodium niobate (BNN) and strontium calcium sodium niobate (SCNN) were investigated. The TB-modified ceramics show promising piezoelectric properties with large-signal piezo coefficients, d(33)*, close to 400 pm/V, planar coupling coefficients, k(p), up to 0.45 and Curie temperatures of approximately 310 degrees C. In addition, the effect of texturing on the undoped (K,Na,Li)(Nb,Ta)O-3 base composition via templated grain growth (TGG) with microcrystalline NaNbO3 templates was examined. Lotgering factors up to 81% and strain enhancements by a factor 1.5 with large-signal values of d(33)* up to 550 pm/V could be achieved in the textured samples.