Shear-mode piezoelectric properties of 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 single crystals

In this paper, 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 (PMNT69/31) single crystals have been investigated on their shear-mode piezoelectric properties as a function of crystal orientation and electrode material using resonance techniques. Three types of electrodes, coated graphite and sputtered Au or Cu, were applied. It was found that the largest stress is produced by applying a field along the 〈11̄0〉 direction combined with a poling along the 〈111〉 direction. In this case, piezoelectric coefficients d15, g15 and electromechanical coupling coefficient k15 had values of 3689 pC/N, 0.0318 V m/N and 93.3%, respectively, for samples with graphite electrode. However, much better piezoelectric properties with d15, g15, and k15 of 5980 pC/N, 0.056 V m/N and 97.0%, respectively, were obtained as the samples with Cu electrode. Our results suggest that these 〈111〉-oriented crystals are promising materials for shear transducer.