The propagation characteristics of shear horizontal waves in [001]𝑐, [011]𝑐 and [111]𝑐 direction polarized 0.72Pb (Mg 1/3 Nb 2/3 )O3-0.28PbTiO3 (PMN-0.28PT) piezoelectric single crystals/polymer periodic laminated composites are studied by using the global matrix method. The numerical results show that the piezoelectric effect has a significant influence on the bandgap width of the composite structure containing [011]𝑐 and [111]𝑐 poled PMN-0.28PT, but little effect on the band structure of the system containing [001]𝑐 poled single crystal. In addition, the first bandgap (FBG) width of the composite structure depends strongly on the poling directions when the filling fraction of PMN-0.28PT is larger than 0.5, and its FBG starting frequency displays no distinct difference among the three polarization directions at all filling fractions. The reported results provide valuable guidelines for designing filters and transducers made of composite structures containing relaxor-based ferroelectric single crystals.

The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear. In this work, we discuss the influence of temperature on two-dimensional (2D) mode coupling effect and electromechanical coupling coefficient of cylindrical [001] c -poled Mn-doped 0.24PIN–0.46PMN–0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio. The electromechanical coupling coefficient k t decreases with temperature increasing, whereas k 33 is largely invariant in a temperature range of 25 °C–55 °C. With the increase of temperature, the shift in the ‘mode dividing point’ increases the scale of the poling direction of the piezoelectric vibrator. The temperature has little effect on coupling constant Γ. At a given temperature, the coupling constant Γ of the cylindrical vibrator is slightly greater than that of the rectangular vibrator. When the temperature changes, the applicability index (M) values of the two piezoelectric vibrators are close to 1, indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.