Enhanced Piezoelectric Properties of Potassium Niobate Single Crystals by Domain Engineering

The engineered domain configuration was induced into potassium niobate (KNbO 3 ) crystals, and the piezoelectric properties were investigated as a function of domain size. First, single-domain treatment was investigated, and a combination of chemical etching and 2-step electric poling treatment was effective. Using the single-domain crystals, all piezoelectric related constants were determined. On the basis of these piezoelectric constants, the d 31 and d 32 surfaces were calculated. The piezoelectric properties of [001] c oriented KNbO 3 single-domain crystals were measured and were completely consistent with the calculated properties. Finally, the engineered domain configurations were induced into KNbO 3 crystals by the control of the temperature and the electric-field along the [001] c direction. The piezoelectric properties of these KNbO 3 crystals with the engineered domain configurations showed much higher values than those of the single-domain crystal. Moreover, the piezoelectric properties increased with decreasing the domain sizes of the engineered domain configuration.