Anisotropic piezoelectric properties of 1-3 ceramic/polymer composites comprising rods with elliptic cross section

This paper is concerned with the study of effective piezoelectric properties of 1-3 ferroelectric ceramic / polymer composites. The aim of this paper is to show the role of a combination of the electromechanical properties of components and microgeometry of the 1-3 composite in determining its anisotropic piezoelectric response. The system of ceramic rods in the form of elliptic cylinders is an important microgeometric factor that influences the piezoelectric coefficients and their anisotropy. Examples of the piezoelectric response and anisotropy are analysed for the 1-3 composites based on either "soft" or "hard" ceramic and having either piezo-active or piezo-passive matrix. Combinations of the ceramic and polymer components are found that provide different volume-fraction dependences of the piezoelectric coefficients d(3j)(*) and g(3j)(*): both monotonic, both non-monotonic d(3j)(*) and non-monotonic g(3j)(*), and vice versa. Examples of volume-fraction dependences of electromechanical coupling factors k(3j)(*) are also considered. A comparison of the effective piezoelectric coefficients calculated by the effective field method and the finite element method is carried out for different compositions in wide ranges of the ratio of semiaxes of the ellipse and of volume fractions of the components. Good agreement between data calculated by means of the aforementioned methods is obtained for the 1-3 structure comprising the elliptic cylinders.