Growth and characterization of Na1/2Bi1/2TiO 3-K1/2Bi1/2TiO3BaTiO3 single crystal piezoelectrics

While lead oxide-based piezoelectrics exhibit some of the highest field-induced strains and most efficient electrical-mechanical energy conversion of known compounds, the toxicity and high vapor pressure during processing of lead oxide ceramics have resulted in an increasing demand for environmentally benign alternative materials with comparable properties. In this work Na_1/2Bi_1/2TiO₃-BaTiO₃ solid solutions have been grown in single crystal form by a flux method. Rhombohedral phase crystals, oriented in the pseudocubic ⟨100⟩ directions, exhibit low-hysteresis actuation with up to 0.24% free strain near the morphotropic phase boundary. Tetragonal phase crystals, oriented in the pseudocubic ⟨100⟩ direction, exhibit free strains as high as 0.85% with greater hysteresis. Actuation energy densities exceed those of optimized polycrystalline lead-perovskites such as Pb(Zr_xTi_1-x)O₃ and Pb(Mg_1/3Nb_2/3)O₃. Significant actuation capability is retained at stresses in excess of 100 MPa