Abstract:
Orientation dependences of electromechanical coupling factors $k_{3j}^*$, squared figures of merit $(Q_{3j}^*)^2$ and their anisotropy factors are studied in the 2–1–2 composites at rotations of the main crystallographic axes of [011]-poled ferroelectric single crystal and bases of ferroelectric ceramic rods. Validity of the large-anisotropy conditions $|k_{33}^*/k_{3f}^*|\ge$ 5 and $(Q_{33}^*/Q_{3f}^*)^2\ge$ 10 is analyzed by considering two rotation modes in the composites based on one of single crystals, 0.935Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$–0.065PbTiO$_3$ or 0.72Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$–0.28PbTiO$_3$. Results are to be taken into account when creating high-effective piezo-active composites for transducers, sensors, acoustic and energy-harvesting devices.
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