Papers by Author: Takeo Tsukada

Abstract: In this study, 0.8 KNbO₃ (KN) -0.2 BaTiO₃ (BT) ceramics were prepared using KN powder with the diameter of 100 nm and BT powders with the diameter of 100, 300, or 500 nm. The relative densities were more than 96 % of the theoretical densities of the samples. The dielectric constant of the samples was temperature-stable at temperatures between-50 and 300 °C and it was found that the dielectric constant of the 0.8KN-0.2BT ceramics increased as the BT diameter increased.

Abstract: ANbO₃ – BaTiO₃ (A=K, Na, or K_0.5Na_0.5) system ceramics were prepared using a conventional sintering method, and their dielectric properties were investigated. It was found that the dielectric constant of KNbO₃-BaTiO₃ and (K_0.5Na_0.5) NbO₃- BaTiO₃ system ceramics did not strongly depend on temperature between 20 and 400 °C, making them useful for capacitor application.

Abstract: Poling characteristics, especially DC poling field (E) dependence of dielectric and piezoelectric properties were investigated to evaluate the domain behavior in lead-free ceramics such as alkali niobate and alkali bismuth titanate ceramics. The domain switching was confirmed by the E to realize minimum dielectric constant (εr), minimum electromechanical coupling factor (k) and maximum frequency constant (fc), because of domain clamping. On the other hand, the domain rotation occurred at the E to obtain maximum εr and minimum fc. These phenomena are observed in the lead-free ceramics as well as PZT ceramics.