Papers by Author: Tanawadee Dechakupt

Abstract: In this study, a room temperature aging behavior of Ba(Ti0.99Fe0.01)O3 was investigated. It was found that the dielectric constant decreased with time and ferroelectric P-E hysteresis loops became constricted loops after aging. Moreover, the room temperature aging behavior under various stresses was also observed. It was found that the relative changes of dielectric constant with time of Ba(Ti0.99Fe0.01)O3 ceramics under stress were lower than those under the stress-free condition. For P-E hysteresis loop measurement, it can be observed that P-E hysteresis loop of Ba(Ti0.99Fe0.01)O3 ceramics became constricted loops and remanant polarizations (Pr), saturated polarizations (Ps) were decreased after aging under all stress levels. These results suggested that the applied stress may partly clamp the domain wall motion, and altered the aging behavior of the ceramics.

Abstract: The microstructure and interface quality of chemical solution deposited barium titanate thin films on Ni foil were studied. Cross-sectional transmission electron microscopy shows that a ~200 nm thick barium titanate film annealed in a controlled oxygen partial pressure consists of equiaxed grains with grain size range of 24-75 nm (~ 42 nm average). NiO was detected after re-oxidation by X-ray diffraction, but not by transmission electron microscopy, suggesting that the oxide is not a continuous barrier layer, but is spatially distributed in the films. Oxygen non-stoichiometry and the existence of C in barium titanate films were observed by electron energy loss spectrometry. In addition, it was found that there is a 5-8 nm thick Ni-Ba alloy developed at the interface between the barium titanate film and Ni foil.