生体適合圧電薄膜に対する第一原理援用トリプルスケール解析の提案

概要

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A computational scheme of first-principles aided triple-scale analysis based on a process crystallography was proposed to design biocompatible piezoelectric thin films fabricated on substrate. To predict the crystal morphology of thin film such as preferred orientations and their ratio, the structural stability of all comformations of crystal cluster on substrate was evaluated by employing pseudo-potential method in density functional theory. Then, the predicted crystal morphology was introduced into micro structure and macro homogenized properties of piezoelectric thin film were estimated through dual-scale finite element analysis based on crystallographic homogenization theory. From the application to the existing biocompatible piezoelectric BaTiO_3 thin films fabricated on SrTiO_3 (110), SrTiO_3 (001) and MgO(100), computational results of the preferred orientations of microstructure and the homogenized dielectric constants of macrostructure had good correlation with experimental ones. Additionally, the proposed computation was applied to a new biocompatible piezoelectric MgSiO_3 thin film, which has been found by first-principles calculations in our previous studies. As a result, the computation indicated that Cr(110) substrate is most suitable for stable crystal growth of MgSiO_3 orientated to [101] direction and it outputs the high piezoelectric stress constants e_<33>=5.39C/m^2 and e_<31>=-3.64C/m^2.
2008-11-25