Application of Pb[(Zn/sub 1/3/Nb/sub 2/3/)/sub 0.91/Ti/sub 0.09/]O/sub 3/ single crystal with giant k/sub 31/ mode to piezoelectric bimorph

Piezoelectric unimorphs and bimorphs were fabricated by utilizing Pb((Zn/sub 1/3/Nb/sub 2/3/)/sub 0.91/Ti/sub 0.09/]O/sub 3/(PZNT91/09) single crystal plates with giant k/sub 31/ over 80%. The electromechanical coupling factors on bending mode (k/sub b/) were 64.7% (PZNT91/09 single crystals) and 20.6% (PZT ceramics) in the case of unimorphs. The k/sub b/'s in bimorphs were 69.8% (PZNT91/09 single crystals) and 31.2% (PZT ceramics), respectively. Furthermore, the PZNT91/09 single crystal bimorph showed the superior piezoelectric properties such as three times larger impedance ratio on the resonant and the anti-resonant frequencies. The displacement of the single crystal devices also showed the excellent characteristics in comparison with the one of the PZT ceramic devices.