Wave band gaps in two-dimensional piezoelectric/piezomagnetic phononic crystals

Abstract

In this paper, the elastic wave propagation in phononic crystals with piezoelectric and piezomagnetic inclusions is investigated taking the magneto-electro-elastic coupling into account. The electric and magnetic fields are approximated as quasi-static. The band structures of three kinds of piezoelectric/piezomagnetic phononic crystals—CoFe 2O 4/quartz, BaTiO 3/CoFe 2O 4 and BaTiO 3–CoFe 2O 4/polymer periodic composites are calculated using the plane-wave expansion method. The piezoelectric and piezomagnetic effects on the band structures are analyzed. The numerical results show that in CoFe 2O 4/quartz structures, only one narrow band gap exists along the Γ– X direction for the coupling of xy-mode and z-mode for the filling fraction f being 0.4; while in BaTiO 3/CoFe 2O 4 composites, only one narrow band gap exists along the Γ– X direction for xy-mode and no band gap exists for z-mode as the filling friction f is 0.5. Moreover, for the new type of magneto-electro-elastic phononic crystal—BaTiO 3–CoFe 2O 4/polymer periodic composite, the band gap characteristics are more superior in the whole considered frequency regions due to the big contrast of the material properties in the two constituents and the effects of the piezoelectricity and piezomagneticity on the band gap structures are remarkable.