Ferroelectrics with periodically layered domain structure: computer simulation of acoustical properties

摘要

Researches exploring the dynamical properties of such smart materials as multilayer structures (MLS's) attract the increasing attention. Particularly, the MLS's consisting of coherent array of antiphase domains have been reproted [1-3]. their acoustial properties and possible applications have been studied both theoretically and experimentally [3-8]. This paper is organized to present a detailed computer simulation study of shear wave propagation in periodic MLS's consisting of infinite, semi-infinite or finite number of antiphase domains. These MLS's in ferroelectric crystals of hexagonal symmetry are assumed to be formed by the alternation of two domain layers with differnet thicknesses an opposite directions of the spontaneous polarization. Shear waves, which are polarized parallel to the domain walls and propagate along the perpendicular to the spontaneous polarization direction, are considered. The corresponding dispersion equations are particular cases of the general equations derived previously for composite piezoelectric structures by using the mathematical approach named by the periodic Hamiltonian system formalism {7,9-14]. The computer experiments have been conducted for hte domain MLS's in BaTiO_3 over a wide range of frequencies and wavelengths. The dispersion relations are discussed as functions of the ratio between thicknesses of two adiacent domains. Results demonstrate the great diversity of spatial localization of diferent modes and their "sensitivity" to the ratio of thicknesses.