Orientation dependence on piezoelectric properties of Bi0.5Na0.5TiO3-BaTiO3-SrTiO3 epitaxial thin films

Orientation-engineered 0.755(Bi0.5Na0.5)TiO3-0.065BaTiO(3)-0.18SrTiO(3) thin films deposited on Nb doped SrTiO3 (N:STO) single crystalline (001), (110), and (111) substrates via a sol-gel process were investigated. Highly epitaxial growth was observed in the as-deposited thin films. Excellent piezoelectric properties are exhibited by the (111) oriented thin films with the highest strain level (0.32%) and local effective piezoelectric coefficient (d(33) = 210 pm/V). Strong orientation dependence of piezoelectric properties on the thin films is attributed to the relative alignment of crystallites and spontaneous polarization vector. These findings are of great significance for piezo-micro electro mechanical systems. (C) 2014 AIP Publishing LLC.