The effect of biaxial texture on the effective electromechanical constants of polycrystalline barium titanate and lead titanate thin films

Effective electromechanical constants as a function of biaxial crystallographic texture in polycrystalline films are modeled using a self-consistent approach. The film is modeled by assuming Gaussian distributions of two Euler angle textures about perfect orientation with varying spread, or full width at half maximum. We see that independent in-plane texturing has little effect on the piezoelectric displacement tensor. Increased out-of-plane texturing gives rise to an enhanced piezoelectric effect for barium titanate films, but not for lead titanate. Twist texturing about these out-of-plane angles shows a further enhancement in the non-shear components of the piezoelectric displacement tensor for both materials. Finally, we use the effective piezoelectric coupling factor as the primary figure of merit for the effective piezoelectric properties of polycrystal devices, thus utilizing all electromechanical constants of this simulation. This quantity shows a primary dependence on the out-of-plane texture.