No abstract

Crystal phase and structural properties in sub-100-nm-thick SrBi2Ta2O9 (SBT) thin films deposited on silicon substrates have been quantitatively investigated by X-ray diffraction (XRD) and X-ray reflection (XRR) analyses. The simulation fitting of XRR showed that the density and the surface roughness of the SBT film increased and saturated as the annealing temperature increased, indicating the phase transformation from fluorite to Aurivillius and the grain growth were enhanced by the high-temperature annealing. The SBT film was composed of small crystals of fluorite-type and Bi-layered Aurivillius phase after crystallization at temperatures of 730–785°C for 1 h. When annealing temperature was higher than 800°C, the film crystallized into a single phase of Bi-layered Aurivillius. It was also shown that the average crystal size in the SBT film increased with annealing temperature and saturated to be ∼75 nm at annealing temperatures higher than 800°C. The annealing temperature dependence of the integrated intensity of the diffraction suggested that the activation energy of the crystallization into the Aurivillius phase was significantly changed at ∼800°C. The change in the activation energy had a close relationship with the structural phase transformation of fluorite to Aurivillius and the grain growth.

For electroosmotic flow (EOF) in a capillary, a method is established to locate the frontal zone between the injected and ejected solutions, based on the change in the electric current required to sustain the EOF when there is a difference of electric conductivity between the injected and ejected solutions. When a certain voltage is applied between the two ends of a capillary filled with a solution, the EOF is generated in the capillary, the flow profile of which is flat, in contrast to that of the Poiseuille flow. Although the EOF moves the frontal zone with constant velocity, the monitored electric current required to sustain the EOF under a constant voltage is found to change according to a hyperbolic function of time. By associating the injected and ejected solutions with two resistances connected in series, an accurate account is given of the change in the electric current while the frontal zone progresses through the capillary.

The existence of the interface current at the methyl alcohol-silica interface was confirmed by infrared observations of the thermal boundary layer (TBL) formed due to Joule heat at the interface. Since the current estimated using the electric conductivity of the bulk phase of the methyl alcohol was 1/10 of the current actually observed, the existence of an interface current flowing in the electric double layer formed at the liquid-solid interface, where the excess cations carry the electric current more effectively than the bulk phase, was confirmed. Since the electric conductivity of the methyl alcohol is extremely low, the infrared rays from the TBL were observed without being impeded by the Joule heat of the bulk phase. Despite the fact that the heat conduction is capable of expanding the TBL, the steady thickness of the TBL was found to be maintained due to radiation loss.