Surface/interface effect on band structures of nanosized phononic crystals

The band structures of transverse waves propagating in a two-dimensional phononic crystal composed of nanosized holes or elastic inclusions embedded in an elastic solid is calculated using the method based on the Dirichlet-to-Neumann map. The surface/interface effect of the nanosized holes/inclusions are taken into account by assuming the Young–Laplace equation at the surface/interface. Both square and triangular lattices are considered. Detailed calculations are presented for two cases: a square or triangular lattice of nanosized holes in an aluminum host and a square or triangular lattice of aluminum inclusions in a tungsten host. The results show that the consideration of the surface/interface effect is significant for nanosized phononic crystals.

► Surface effect of nanosized phononic crystals is studied based on the Young–Laplace equation.
► Negative surface modulus results in lowering and broadening of the bandgap.
► Positive surface modulus results in rising and narrowing of the bandgap.