残留応力による薄膜積層構造の圧電応答の増幅効果に関する数値解析

抄録

Piezoelectric thin films, which are widely used for actuators and sensors in various devices, generally have a laminated structure consisting of a substrate, buffer and piezoelectric layers. If the piezoelectric layer is fabricated at high temperature, some residual stresses occur due to difference of thermal expansion among layers. In case of functional materials, the residual stresses, which often reduce strength of structural materials, have the possibility to enhance piezoelectric performance by coupling effect. In this paper, the residual stresses in piezoelectric thin films were analyzed and their influence on piezoelectric performance was computationally revealed. Additionally porous ceramics were introduced into the buffer layer, and then elastic modulus and thermal expansion coefficient of the buffer layer were changed by porosity. A multiscale simulation based on homogenization theory was employed to evaluate material properties of porous buffer layer, and finite element simulation was applied to estimate the performance of piezoelectric thin film. The influence of porosity on material properties and the performance of piezoelectric thin film on porous buffer layer and substrate were investigated and the effective condition was discussed.