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Silica containing uniformly dispersed Ni nanoparticles has been synthesized by a precursor solution method, involving heat treatment and reduction stages, and the transformation of the Si–Ni–O precursor into the composite powder has been investigated systematically to determine the formation mechanism of the nanoparticles. During heat treatment, nickel oxide nanoparticles are found to form simultaneously with the Si–O network, as decomposition of the alkoxy ligand and nucleation of NiO nanoparticles, both occur at around 300°C. The formation of ionically bound Si–Oδ−–Niδ+ units plays a key role in anchoring the NiO in the Si–O network and impeding further crystalline growth. Moreover, the formation of the Si–O2−–Ni2+ interactions in the composite of dispersed NiO in SiO retard the reduction of NiO, resulting in a characteristic microstructure consisting of highly dispersed metallic Ni nanoparticles within an Si–O matrix. This nickel–silica composite is expected to show enhanced reversible hydrogen adsorption, making it attractive for use in separation membranes with high hydrogen selectivity.

In this study, the syntheses of bulks of Y-zeolite were attempted by a hydrothermal hot-pressing (HHP) method with various conditions such as the amounts and concentrations of NaOH solution, reaction temperatures, and reaction times. Dense bulks of Y-zeolite were successfully obtained by this HHP method. Under an optimum synthetic condition of HHP, solidified bulks of Y-zeolite possessed translucency with high values of specific surface area. Transmission electron microscopy observation of these translucent bulks of Y-zeolite showed that their microstructures were densified like polycrystalline ceramics sintered by heat treatments and no amorphous phase was observed at the boundaries of Y-zeolite grains. As a result, in these unique bulks of Y-zeolite synthesized by the HHP method, the microporous network was thoroughly connected at the grain boundaries of Y-zeolite.

Zeolite materials are very sensitive to electron beam irradiation. Therefore, there have been only limited attempts to characterize their structures using high-resolution electron microscopy (HREM). The sensitivity to the electron beam depends strongly on the Si/Al ratio in zeolites. A slow-scan, charge-coupled-device (CCD) camera provides the possibility to observe materials using HREM with very low beam doses. In this study, this method was applied to observe sensitive materials such as zeolite type A and type Y, and HREM images were recorded without any damage caused by electron irradiation under a dose density less than 0. 2 A /cm2. It was found that fine channel structures, cleavage planes, and the electron irradiation process in the zeolites could be characterized using HREM with the slow-scan CCD camera.

Zirconia (ZrO2) particles (average diameter, 30 nm) were observed in an in situ heating experiment up to 1200°C using a 400-kV high-resolution electron microscope. Thermal vibration of atoms on a (001) surface plane was observed at 1100°C. At 1200°C, grain growth and sintering phenomena were recorded on a videotape, showing (100) lattice planes migrating on a surface of a particle. Direct observation of the sintering process on a lattice level was accomplished for the first time.