Depending on the degree of polymerization of the zirconium species in zirconium oxychloride solutions, three kinds of microporous clay intercalation compounds have been prepared by cation exchange of a swelling clay with the zirconium polynuclear ionic species. These are products with 7-, 12-, and 14-Á interlayer spacings (=gallery heights). The major species in zirconium oxychloride solutions at room temperature is the zirconium tetramer, [ 4(0 )8+ ( 20) 6-](8" )+, giving the intercalation compound with a 7-A interlayer spacing. Upon hydrolytic polymerization of the zirconium tetramer in solution, the more highly polymerized zirconium species are generated that can provide the intercalation compounds with 12or 14-Á interlayer spacings; the concentration of halogen ions in the solutions governs the kinds of the intercalates. The two polymeric species forming the intercalates with 12-and 14-Á interlayer spacings are composed of three-dimensionally polymerized clusters based upon the tetramer. Examination of the intercalation compounds sheds light on the structure of the ionic species in solution.

The potential of the electrospray technique in analyzing the structure of nonspherical colloidal particles that are below 100 nm in volume-equivalent diameter was demonstrated by online size measurement using a differential mobility analyzer (DMA) with a condensation nucleus counter (CNC) system. The measured mobility of gold nanorods was confirmed by electron microscope images and the theoretical calculation of particle mobility using the dynamic shape factor and slip correction factor. To evaluate the mobility, rod particles were modeled as both a cylinder and a prolate spheroid. This study also showed that the organic surfactant coated on rod particles might be removed and that the rod particles became spherical upon the elevation of the ambient temperature during the gas-phase dispersion of colloidal nanoparticles. Moreover, the thickness of the surfactants coated on rod particles was estimated by comparing the theoretically and experimentally obtained mobilities.

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We studied the synthesis of nanostructured oxide/hydroxide within the two-dimensional nanospace of a pillared interlayered solid (alumina-pillared clay). A nickel(II) hydroxide unit layer was introduced into the pore of the pillared clay by adding a base to a nickel(II) nitrate solution containing the pillared clay calcined over 300 °C. The formation of the lowdimensional nickel(II) hydroxide was evaluated by X-ray diffraction analysis, elemental analysis, surface area measurements, temperature-programmed reduction measurements, and X-ray photoelectron spectroscopy measurements. In situ growth of nanostructured NiO in the pores was performed by the heat treatment of the intracrystalline nickel(II) hydroxide. The Ni 2p binding energy of the intracrystalline nickel(II) hydroxide was the same as that of bulk nickel(II) hydroxide. However, the intracrystalline NiO had a Ni 2p binding energy ca. 2-3 eV higher than that of bulk NiO. These phenomena were rationalized in terms of the structure of the pores of the pillared clay and the structures of nickel(II) hydroxide and NiO. The intracrystalline nickel(II) hydroxide was less reducible than bulk nickel(II) hydroxide; Ni metal was afforded outside the pores upon reduction in hydrogen at 500 °C.

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