Ferroelectric and piezoelectric properties of lead-free Bi0.5Na0.5 TiO3-Bi0.5K0.5TiO3-BaTiO3-thin films near the morphotropic phase boundary

Abstract

Lead-free Bi0.5Na0.5TiO3 (BNT)-Bi0.5K0.5TiO3 (BKT)-BaTiO3 (BT) piezoelectric thin films with compositions near the morphotropic phase boundary (MPB) were deposited by metal-organic solution deposition on Pt/Ti/SiO2/Si (100) substrates. The compositional dependences of their microstructure and ferroelectric/piezoelectric properties were investigated. The results indicated that all the thin films have a single-phase perovskite structure and show outstanding electrical properties at room temperature. We found that the thin film with a composition of 0.884BNT-0.08BKT-0.036BT showed the best structural and electrical properties, with a dielectric constant, remnant polarization, and effective piezoelectric constant of similar to 638, similar to 27 mu C/cm(2) and similar to 79 pC/N, respectively. We suggest that these superior properties are due to this sample's high degree of alignment of ferroelectric domains in the MPB region and largest grain size. (C) 2013 Elsevier B. V. All rights reserved.