Giant piezoelectric property of (110) oriented [formula omitted] films

Abstract

A phenomenological Landau-Devonshire theory is applied to investigate the phase diagrams and physical properties of (110) oriented BaxSr1−xTiO3 films. New ferroelectric phases, such as the tetragonal a1 phase and the orthorhombic a2c phase, appear in the “misfit strain-temperature” phase diagrams for (110) oriented films compared with that of (001) oriented films. Moreover, the orthorhombic a2c phase, and the tetragonal c phase and the triclinic γ phase are stable at low temperature for x=0.5 and x=0.7, respectively. The ferroelectric, dielectric, and piezoelectric properties strongly depend on the misfit strain and electric field. (110) oriented Ba0.7Sr0.3TiO3 film has the larger ferroelectric polarization and piezoelectric coefficient than that of Ba0.5Sr0.5TiO3 film. The giant piezoelectric coefficient of 340pm/V is obtained at the electric field of 50KV/cm in (110) oriented Ba0.7Sr0.3TiO3 film, which is comparable with the values of Pb(Zr1−xTix)O3 and (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 films. It makes (110) oriented BaxSr1−xTiO3 films suitable for applications in electromechanical devices.