Piezoelectric Properties of Lead-Free (Na,Bi)TiO₃–BaTiO₃(001) Epitaxial Thin Films around the Morphotropic Phase Boundary

Abstract

The piezoelectric properties and the crystallographic nature of (1-x)(Na,Bi)TiO3–xBaTiO3 (NBT–BT) thin films around the morphotropic phase boundary (MPB) composition (x=0.05–0.10) were studied. NBT–BT thin films were grown epitaxially on Pt(100)/MgO(100) substrates by RF magnetron sputtering and exhibited highly (001)-oriented single-phase perovskite with a tetragonal structure. A maximum piezoelectric coefficient e31 of -14.4 C/m2 was obtained at the x = 0.07 composition of the tetragonal side near MPB (x = 0.06). These results indicate that NBT–BT thin films around the MPB are a promising lead-free replacement for Pb(Zr,Ti)O3 (PZT) based applications.