Giant acoustic stop bands in two-dimensional periodic arrays of liquid cylinders

Periodic binary systems can give rise to complete acoustic band gaps (i.e., stop bands) within which sound and vibrations are forbidden. We compute the band structure for two-dimensional (2D) periodic arrays of long water cylinders surrounded by mercury host. Complete acoustic stop bands are found for both square and hexagonal lattices. We emphasize that such a simple 2D inhomogeneous system of liquids exhibits the widest stop bands ever reported for elastic as well as dielectric composites. We find gap/midgap ratios as high as similar to 1. For mercury cylinders surrounded by water the gaps obtained are much smaller. (C) 1996 American Institute of Physics.