Papers by Keyword: Engineered Domain Configuration

Abstract: To induce fine engineered domain configurations into potassium niobate (KNbO3) single crystals, two kinds of methods were performed, i.e., (1) high DC electric field exposure along the opposite direction of polarization of KNbO3 single-domain crystals at room temperature, and (2) introduction of randomly oriented fine domain configuration by heat treatment at 700 °C and then high DC electric field exposure along [001]c direction of KNbO3 multidomain crystals at room temperature. When the method (1) was performed, finally, the poled KNbO3 crystals became to single-domain state again through the formation of multidomain state. On the other hand, the KNbO3 multidomain crystals were obtained by using the method (2), and an enhancement of piezoelectric-related properties was observed.

Abstract: The phase transition behaviors of the [111]c oriented barium titanate (BaTiO3) single crystals (the subscript c means the cubic notation system) were investigated as functions of temperature, uniaxial stress and electric fields. These results suggested that above Tc, combination between uniaxial stress and electric fields might be effective for a poling treatment of BaTiO3 single crystals. Thus, a new poling method for BaTiO3 single crystals was proposed using control of temperature, uniaxial stress and electric fields in this study.

Abstract: For the [111] oriented barium titanate (BaTiO3) single crystals, the patterning electrode was applied to induce the finer engineered domain configurations with domain size of 3 2m. The poling treatment was performed at 134 °C under electric fields below 6 kV/cm to inhibit the burning of the patterning electrode with photoresist. As the results, the gradient domain sizes from 3 to 8-9 2m were induced into the 31 resonator. The d31 was measured at -243.2 pC/N, and this value was almost 70 % of the expected d31 of –337.7 pC/N for the resonator with domain size of 3 2m. This difference was originated from lower applied electric field below 6 kV/cm. However, this study was revealed that the patterning electrode was very powerful tool to induce much finer domain sizes below 5 2m.

Abstract: For potassium niobate (KNbO3) single crystal, the 31 resonators with the highest piezoelectric constant d31 were designed using transformation of axis. We confirmed that the engineered domain configurations with maximum d31 of –55.1 pC/N was caused by a combination between two polarization with polar directions along [101]c and [-101]c directions. Moreover, if there are larger piezoelectric constants from domain wall region, we can expect the much higher piezoelectric properties. To induce the above domain configuration, a new poling method using patterning electrode was investigated. In this study, the two methods on the basis of temperature-induced phase transition at 207 °C and electric-field-induced phase transition at room temperature were investigated.