Tunable passband in one-dimensional phononic crystal containing a piezoelectric 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 single crystal defect layer

• Investigation of band structure in 1D phononic crystal containing a PMN–0.38PT defect layer.
• Tunable frequency location of passband by external voltage on piezoelectric defect layer.
• Dependence of passband bandwidth on the acoustic impedance ratio of constitutive layer.

Longitudinal acoustic wave propagation in one-dimensional phononic crystal containing a 0.2 mol% Fe-doped relaxor-based ferroelectric 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 (PMN–0.38PT) single crystal defect layer is theoretically studied using the transfer matrix method. A passband can be produced in the stopband when the inserted PMN–0.38PT layer with thickness around its half wavelength. The frequency of the passband is closely dependent on the PMN–PT strain coefficient, suggesting that the band structure of phononic crystal is tunable by applying external electric field onto the piezoelectric crystal. Also, we investigated the influence of acoustic impedance of periodic constitutive materials (layers A and B) on the passband, where the bandwidth of the new passband becomes narrower as the acoustic impedance ratio of layer A and B (ZA/ZB) increase. The simulated results provide valuable guidance for designing tunable acoustic filters and switches made of phononic crystal consisting of the piezoelectric defect layer.