Influence of filling fraction on the band gaps of two-dimensional piezoelectric phononic crystals in radio frequency

This paper has studied the influence of filling fraction on the band gaps of two-dimensional (2-D) piezoelectric phononic crystals (PnCs) in radio frequency (RF). The 2-D piezoelectric PnCs consists of tungsten (W) stubs on the finite slab of 128°YXLiNbO3 substrate. With Bloch periodic theorem, the single cell model was built using the three-dimensional (3-D) finite element method (FEM). Based on the 3-D FEM model, band structures of the 2-D piezoelectric PnCs were calculated with different filling fractions. Results show that with the increase of the filling fraction, amount of the band gaps increase from one to two, the width of the first band gap becomes narrower and the second band gap become wider firstly and then become narrower, but all these widths become convergent. These results are useful for the applications of the 2-D piezoelectric PnCs in the RF devices as broadband filters and multi-channels filters.