Piezoelectric Bimorph with Giant Electromechanical Coupling Factor of Bending Mode Nearly 70 percent Fabricated by Low Symmetry Mono-Domain Pb[(Zn_(1/3)Nb_(2/3))_(0.09)Ti_(0.09)]O_3 Single Crystals

摘要

Piezoelectric unimorphs and bimorphs were fabricated by utilizing (100) plane Pb[(Zn_(1/3)Nb_(2/3))_(0.91) Ti_(0.09)]O_3(PZNT91/09) single-crystal plates with giant k_(31) over 80 percent, which appeared in the case of a phase with low crystal symmetry. The electromechanical coupling factors on bending mode (k_b) were 64.7 percent (PZNT91/09 single crystals) and 20.6 percent (PZT ceramics) in the case of unimorphs. The values of k_b in bimorphs were 69.8 percent (PZNT91/09 single crystals) and 31.2 percent (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 single-crystal devices possessed the excellent displacement characteristics in comparison with the ones of the PZT ceramic devices.