Proposition of a First-Principles Aided Triple-Scale Analysis for Biocompatible Piezoelectric Thin Films

A process crystallography algorithm based on the first-principles aided triple-scale analysis is newly developed to design biocompatible piezoelectric thin films fabricated on a substrate. The pseudo-potential method within the density functional theory was used to predict the crystal morphology of thin film, such as preferred orientations and their fractions as well as the structural stability of possible conformations of crystal clusters on substrates. A crystal morphology at the micro scale was selected and macro homogenized properties of piezoelectric thin film were obtained through a double-scale finite element analysis based on the crystallographic homogenization theory. Further, our analysis was applied to the existent biocompatible piezoelectric BaTiO3 thin films, fabricated on SrTiO3(110), SrTiO3(001) and MgO(100) substrates. Numerical results of the preferred orientations of the micro structure and the homogenized dielectric constants of the macro structure showed good agreements with experimental results. Additionally, the proposed process crystallography algorithm was applied to the new biocompatible piezoelectric MgSiO3 thin film generation, which has been found by the first-principles calculation in the previous study. As a result, the computational result indicates that the Cr(110) substrate is most suitable for stable crystal growth of [101] oriented MgSiO3 and shows high piezoelectric stress constants, such as e33= 5.39 C/m2 and e31= -3.64 C/m2.