Characterization and modeling of ferroelectric thin- films and 1-3 composites

This contribution shows that the combination of experimental characterization and theoretical modeling is a powerful method for the further development and tailoring of smart materials. In a first example, the piezoelectric properties of ferroelectric thin films can strongly be influenced by mechanical clamping on the surrounding media, i.e. the substrate, the electrode as well as the surrounding unpoled film. The influence of these clamping effects on the measurement of the piezoelectric coefficient d(33) is investigated. A Finite Element Method (FEM) modeling shows that for common film and substrate dimensions the measurable piezoelectric coefficient d(33,m) can reach only 50,, of the value under free conditions. In the second part, 1-3 composites with different arrangements and volume fractions of the piezoelectric ceramic embedded in a polymer matrix were investigated with emphasis their effective dielectric and electromechanical properties. FEM modeling and analytical solutions are used to predict the effective material properties of the composite. Additionally, the influence of the arrangement of the active phase in the matrix on the dynamic properties was investigated.