Piezoelectric properties of potassium niobate single crystals by domain engineering

Potassium mobate (KNbO3) single crystals were grown by a TSSG method. At first, the electric field was applied along the [001](c) (cubic notation system) direction of KNbO3 crystals to induce the engineered domain configurations into KNbO3 Crystals. Prior to domain engineering, the piezoelectric properties of [001](c)-oriented KNbO3 single-domain crystals were measured. These measurement values were completely consistent with the calculated apparent d(31) and d(32). Finally, the engineered domain configurations were induced into KNbO3 crystals. As a result, piezoelectric properties increased with decreasing domain sizes of the engineered domain configuration. However, the symmetry of the KNbO3 crystals was mm(2), and there were four kinds of domain structures such as 90degrees, 180degrees, 60degrees and 120degrees domains. Thus, the engineered domain structure induced in this study was very complicated, and the piezoelectric properties were also dependent on domain pattern and kinds of domain walls.