We reported on the hydrogen desorption properties, microstructure, kinetics, and decreased, compared with that of the sample ball-milled for 0.02 h. TEM observations revealed that the distribution of Nb 2 O 5 in MgH 2 was gradually improved during ball-milling. On the other hand, we confirmed by XPS that in the sample ball-milled for 0.2 h, Nb 2 O 5-x phase(s) existed at least on the surface. It can be suggested that these deoxidized Nb 2 O 5-x phases eventually decrease E a as substantial catalyst rather than Nb 2 O 5 itself.

We present the results of an investigation of the microstructural properties of layered-structure perovskite SrBi2Ta2O9 films grown by Flash-MOCVD, conventional CVD, and MOD. The films grown by Flash-MOCVD on Pt electrode layers, were polycrystalline and showed acceptable ferroelectric properties and low leakage. TEM showed that the individual crystallites were of high quality and, on average about 300nm in diameter. TEM also gave some indications of a disordered phase interspersed amongst the crystallites.A complete, high-resolution set of XPS spectra gathered from these films confirmed that the basic perovskite structures were predominately single phased but that they were, in all cases, accompanied by a significant amount of mobil clusters of Bi metal. We speculate that this Bi metal corresponds to the disordered phase seen by TEM and show that appropriate ozone annealing is able to remove all evidence of it.

We carried out in-situ observation on the catalytic effect of Nb2O5 in MgH2 by using a high voltage transmission electron microscope (HVEM). We synthesized two kinds of samples, which were prepared by ball milling and by hand mixing. In milled sample, Nb2O5 was not confirmed from high resolution images, however, NbO was identified. As the temperature increased, the decomposition of MgH2 proceeded, while Mg formed and grew. It suggested that NbO had the catalytic effect to promote the dehydrogenation of MgH2. In mixed sample, which was prepared to clearly observe the boundary between the catalyst and Mg phase, it was revealed that the dehydrogenation started from the boundary of MgH2 and Nb2O5. This result suggested that the dehydrogenation could proceed with hydrogen diffusion from MgH2 through Mg phase to the boundary.