%0 Journal Article %K Lead %K Thin films %K Polycrystals %K Polarization %K Epitaxial growth %K Piezoelectricity %K Ferroelectric thin films %K Microelectromechanical devices %K Extrinsic effects %K In-plane strains %K Piezoelectric coefficients %A J Ouyang %A Ramamoorthy Ramesh %A A.L Roytburd %B Applied Physics Letters %D 2005 %G eng %P 1-3 %R 10.1063/1.1899252 %T Intrinsic effective piezoelectric coefficient e 31,f for ferroelectric thin films %V 86 %X As a function of film orientation, the intrinsic effective piezoelectric coefficient e31,f is generally formulated for a substrate-constrained ferroelectric film. Numerical results are obtained for Pb (Zrx Ti1-x) O3 (PZT) thin films with tetragonal and rhombohedral compositions. It is illustrated that the optimal orientation for e31,f are close to [001] orientation in both tetragonal and rhombohedral PZT films and the maximum calculated e31,f is about -30 Cm2 on the rhombohedral side of the morphotropic phase boundary. © 2005 American Institute of Physics.