Theoretical approach to effective electrostriction in inhomogeneous materials

An analytical approach is developed for the effective electrostriction, a n onlinearly coupled electromechanical effect, in inhomogeneous materials bas ed on Green's-function method. For an isotropic composite containing random ly oriented ferroelectric crystallites with cubic symmetry, we derive the f irst effective-medium-like formulas for calculating its effective electrost rictive coefficients. The effects of microstructural features (such as volu me fraction, crystallite shape and orientation, and connectivity of phases) on the effective electrostrictive coefficients are illustrated numerically and discussed. The calculations show that it is possible to develop new el ectrostrictors combining large electrostriction with mechanical flexibility by choosing the best combination of ferroelectric ceramics and polymer.