Theoretical investigation of the intrinsic piezoelectric properties for tetragonal BaTiO3 epitaxial films

The orientation dependences of the converse longitudinal piezoelectric constant d33,f, and the in-plane converse piezoelectric constant e31,f, are calculated for tetragonal barium titanate epitaxial films. The calculations demonstrate that both e31,f and d33,f have their maximum values along an axis close to the (1 1 1) direction of the pseudo-cubic system, which are similar to the orientation dependence results for a tetragonal BaTiO3 single crystal. The calculated piezoelectric constants for a (1 1 1) oriented BaTiO3 epitaxial film (e31,f = −23 C/m2, d33,f = 124 pm/V) suggest that it is a good candidate material for lead-free MEMS applications.