Acoustic waves with the in-plane polarization in piezoelectric cubic structures

In this paper, calculations of the phase velocity V ph of the dispersive nine-partial Rayleigh type waves (RTW9) were introduced in dependence on the kh (k is the wavenumber, and h is the layer thickness). The layered systems, consisting of a layer of Bi 12 SiO 20 on a substrate of Bi 12 GeO 20 , and the reverse configurations were investigated. The calculated dispersion curves of the RTW9 lowest-order modes with both metallized and free surfaces have shown the existence of the non-dispersive nine-partial Zakharenko type waves (ZTW9) polarized like the Rayleigh waves. The non-dispersive ZTW9-waves split the RTW9 lowest-order modes into sub-modes with different dispersions, V ph > V g and V ph < V g , where V g is the group velocity. The RTW9 phase velocity V ph is confined within a narrow V ph -range that can be convenient for some technical devices. Also, cubic crystals with strong piezoelectric effect can be used for different cubic-structure magnetoelectric devices. It was found that the coefficient of electromechanical coupling (CEMC) K 2 for the RTW9 first type has its maximum value at kh ~ 5 for the structure Bi 12 SiO 20 /Bi 12 GeO 20 . The second type of RTW9-waves was also studied, which can propagate only in the structure Bi 12 SiO 20 /Bi 12 GeO 20 , because there is the condition V t (Bi 12 GeO 20 ) > V t (Bi 12 SiO 20 ) for the speed V t of the bulk transverse wave, V t = [(C 55 /ρ)(1 + K 02 )] 1/2