Enhanced piezoelectric properties of KNbO/sub 3/ crystals by domain engineering

Potassium niobate (KNbO/sub 3/) single crystals were grown by a TSSG method. At first, the electric field was applied along [001]/sub c/ (cubic notification system) direction of KNbO/sub 3/ crystals to induce the engineered domain configurations into KNbO/sub 3/ crystals. Prior to domain engineering, the piezoelectric properties of [001]/sub c/ oriented KNbO/sub 3/ single domain crystals were measured. These measurement values were completely consisted with the calculated apparent d/sub 31/ and d/sub 32/. Finally, the engineered domain configurations were induced into KNbO/sub 3/ crystals. As a result, piezoelectric properties increased with decreasing domain sizes of the engineered domain configuration. However, the symmetry of the KNbO/sub 3/ crystals was mm2, and there were four kinds of domain structures such as 90/spl deg/, 180/spl deg/, 60/spl deg/ and 120/spl deg/ domains. Thus, the engineered domain structure induced in this study was very complicated, and the piezoelectric properties were also depended on domain pattern and kinds of domain walls.