A kaolinite-pyridine intercalation compound was prepared using hydrated kaolinite as an intermediate. Hydrated kaolinite having a basal spacing of 10 Å was treated with pyridine to form a well-ordered intercalation compound having a basal spacing of 12.0 Å. Infrared spectroscopy indicated the presence of hydrogen bonding between the hydroxyls of the kaolinite and the pyridine. 29Si nuclear magnetic resonance spectroscopy with cross polarization and magic-angle spinning revealed that intercalated pyridine affected the environment of silicon. The mono-substituted pyridine derivatives were also intercalated with hydrated kaolinite. On the basis of the basal spacings of the intercalation compounds and the stabilities of the derivatives between the layers, the pyridine appeared to be in an approximately perpendicular position, with the nitrogen facing the gibbsitic sheets.

A kaolinite-polymer intercalation complex was apparently formed for the first time by the polymerization of acrylonitrile between the kaolinite layers. A kaolinite-ammonium acetate intercalation complex was dispersed in acrylonitrile monomer. The monomer was apparently incorporated between the layers by displacing intercalated ammonium acetate. After the removal of excess monomer, the intercalation complex was heated to cause polymerization. The resulting kaolinite-polyacrylonitrile (PAN) intercalate showed a basal spacing of ∼ 13–14 Å. On heating the complex at 220°C for 1 hr in air, the spacing decreased slightly. The hydrogen bond between the hydroxyls of kaolinite and probably the C≡N group of PAN was not affected after heating at 220°C. Even after heating at 400°C, the layers expanded. Because the starting kaolinite-ammonium acetate intercalation complex decomposed at a much lower temperature, these observations strongly suggest the presence of PAN between the layers.

Acrylamide has been polymerized between the layers of kaolinite by heat treatment. Acrylamide monomer was first intercalated by the displacement reaction between a kaolinite-N-methylformamide (NMF) intercalation compound and a 10% acrylamide aqueous solution. The resulting intercalation compound showed a basal spacing of 11.3 Å. Infrared (IR) spectroscopy and 13C nuclear magnetic resonance spectroscopy with cross polarization and magic angle spinning (13C CP/MAS-NMR) indicated the replacement of NMF by acrylamide. IR spectroscopy also showed the formation of hydrogen bonds with the hydroxyls of kaolinite. When the kaolinite-acrylamide intercalation compound was heated at 300°C for 1 hr, the basal spacing increased to 11.4 Å, and IR and 13C CP/MAS-NMR showed the disappearance of C=C bonds, indicating the polymerization of acrylamide. The heat-treated kaolinite-acrylamide intercalation compound was resistant to 30 min-washing with water, whereas the untreated kaolinite-acrylamide intercalation compound collapsed after the same treatment, an observation consistent with acrylamide polymerization between the layers of kaolinite. IR spectroscopy revealed that polyacrylamide was hydrogen bonded to kaolinite, but in a manner different from the hydrogen bonding of acrylamide.

Kaolinite was hydrothermally synthesized from two kinds of silica-alumina gels to examine the effect of the structure of the starting material. Two kinds of gels were prepared by precipitation at different pH conditions (pH = 9.6 and 4.2) from solutions containing water glass and aluminum sulfate. Na ions in the gels were removed with a resin before the hydrothermal treatment, but a slight amount of sulfate ions was still present in the gels. The nuclear magnetic resonance spectra of the starting gels suggested that the gel prepared at pH 9.6 consists of networks with alternating SiO4- and A1O4-tetrahedra (partially AlO6-octahedra), whereas the gel prepared at pH 4.2 consists of a sheet structure related to allophane. After the hydrothermal treatment at 220°C for 9 days, kaolinite particles with spherical shape were obtained from the former gel, and platy kaolinite was crystallized from the latter one. The difference in morphology of synthetic kaolinite was attributable to the structures of the starting gels, and the pH values in the hydrothermal reactions were not very significant to the morphology.

Silanol groups in protonated magadiite (H-magadiite) were characterized by 1H and 2H solid-state nuclear magnetic resonance (NMR). H-magadiite and deuterated (D) magadiite were synthesized by the treatment of Na-rich magadiite with 0.2 N HC1 and 0.2 N DC1, respectively. In the 1H NMR spectrum measured at room temperature, silanol groups of H-magadiite showed two signals at 3.75 and 5.70 ppm, indicating that two types of silanol groups were present. The ratio of silanol groups associated with strong hydrogen bonding (5.70 ppm) to those with weaker hydrogen bonding (3.75 ppm) was 2 to 1. The 2H NMR spectra of deuterated magadiite were measured in the temperature range from 150 to 440 K. In the spectra measured at temperatures below 294 K, silanol groups showed Pake doublet patterns. These patterns were composed of two components corresponding to the two types of silanol groups shown in the 1H NMR analysis. Both silanol groups produced wobbling motions with increasing temperature. Above 294 K, the profile of the Pake doublet pattern was transformed gradually to a near triangular pattern, indicating that the silanol groups underwent other motions also, such as a two-site jump.

A reduced layered tungstic acid with a double-octahedral structure was prepared by acid treatment of an Aurivillius-type Bi2W2O9 in the presence of Sn2+ ions. While the color of the product formed by acid treatment with no Sn2+ ions present, H2W2O7, was yellow, a blue powder was obtained after the acid treatment in the presence of Sn2+ ions. No notable change in the morphology was observed after acid treatment. The X-ray diffraction pattern of the product acid-treated in the presence of Sn2+ ions was very similar to that of H2W2O7. Essentially all the Bi3+ ions were lost upon acid treatment, indicating the occurrence of selective leaching of bismuth oxide sheets in Bi2W2O9. A UV-visible absorption spectrum and XPS analysis demonstrated that the W6+ ions were partially reduced to W5+ ions, and the number of protons in the product was correspondingly 2.4 per [W2O7]. These results suggest the successful formation of a reduced layered tungstic acid, H2.4W2O7.

A protonated form of a layered perovskite was prepared from an Aurivillius phase Bi2SrNaNb3O12via acid treatments, and the effect of the type of mineral acids was investigated. The treatment with HX (X = Cl, Br, I) resulted in the formation of a protonated form H1.8[Sr0.8Bi0.2NaNb3O10], while no reactions were observed for HNO3 and H2SO4 under the present experimental conditions. All the products obtained by HX-treatments exhibited layered structures and the structures of the perovskite-like slabs were preserved.

A kaolinite-organic intercalation compound containing methanol was proved to be a versatile host for further displacement reaction with alkylamines. Kaolinite-organic intercalation compounds with polar molecules, such as N-methylformamide (NMF) and formamide, were used as the starting materials. After stirring the kaolinite-NMF intercalation compound with methanol, the basal spacing increased to 1.11 nm. The 13C MAS NMR result of the product indicated that methanol was intercalated into kaolinite by partial displacement with NMF. By use of the methanol-treated kaolinite intercalation compound as the intermediate, alkylamines were intercalated into the interlayer space of kaolinite by displacing with methanol.

Polycrystalline samples of Na1-xLnxNbO3 (Ln=La, Nd, Sm, Gd) were synthesized by solid-state reactions. Reduced niobates were obtained as single-phase perovskites for x=0.05 and 0.1 when Ln=La and Nd and x=0.05 when Ln=Sm. The Gd-substituted samples could not be prepared under the synthetic conditions studied. Compositional analysis of the products revealed a slight amount of sodium loss during synthesis. The structural parameters obtained from Rietveld analysis revealed an increase in unit-cell volume. All of the obtained samples showed semiconducting behavior. Similar semiconducting behavior was observed for the same x value, suggesting the weak influence of the different Ln species to the electrical properties.

Gallium nitride (GaN) was prepared by the pyrolytic conversion of both [Ga(NEt2)3]2 and its ammonolysis product at 600 °C for 4 h under Ar. The pyrolyzed residues were analyzed by X-ray powder diffraction and scanning electron microscopy, and the pyrolysis processes of the precursors under He were investigated by thermogravimetry-mass spectrometry. The XRD pattern of the pyrolyzed residue of [Ga(NEt2)3]2 showed well-resolved peaks due to a mixture of cubic and hexagonal close-packed layers of GaN. The broad XRD pattern of the pyrolyzed residue of the ammonolysis product was also attributed to the mixture of cubic and hexagonal close-packed layers of GaN. For the pyrolysis of [Ga(NEt2)3]2, the evolution of hydrocarbons was extensively observed at relatively high temperature, but a large amount of carbon (11 mass%) was still detected in the pyrolyzed residue. On the other hand, the amount of carbon was only 1.1 mass% in the pyrolyzed residue of the ammonolysis product. The pyrolysis results of the ammonolysis product under Ar were very similar to those of [Ga(NEt2)3]2 under NH3.

The hydrolysis and initial condensation processes of the mixtures of TEOS and MTES have been studied by GC-MS and 29Si-NMR in the systems with TEOS:MTES:ethyl alcohol:water:HCl=1:1:14:28:6×1O-4 and 0.5:1.5:14:28:6×10-4. Thedimer CH3(HO)2SiOSi(OH)3 possessing both TEOS- and MTES-derived units was identified, indicating that the condensation between a hydrolyzed TEOS-derived monomer and a hydrolyzed MTES-derived monomer was one of dominant dimerization.

Methylviologen dication was intercalated to some layered semiconducting oxides, and the photoinduced electron transfer between the hosts and the guest was investigated. K4 Nb6O17, H2 Ti4O9, and HTiNbO5 were used as the layered oxides. The arrangements of methylviologen in the interlayers were deduced from the XRD results. UV irradiation of the intercalation compounds caused electron transfer from the hosts to the guest to form methylviologen radical cations. The radical cations were stable within a few minutes even in the presence of oxygen, and the decaying rates altered with the hosts. The difference was discussed on the basis of the structure of the intercalation compounds.

In order to develop new precursors for the preparation of titanium nitride, a Ti alkoxide-nitrogen containing polyol condensation product was prepared and heat-treated. A stoichiometric mixture of titanium tetra-isopropoxide (Ti(OC3H7)4) and triethanolamine (N(CHM2H4OH)3) was heated at ca. 200°C under reduced pressure. The distilled liquid was isopropyl alcohol and its amount indicated that the transesterification reaction proceeded almost quantitatively.

The condensation product was a transparent glassy solid on cooling to room temperature. Thermal treatment of the condensation product at 1600°C in a nitrogen flow yielded titanium nitride (TiN1-x-yCxOy) as the main phase with a small amount of Ti3O5. The thermal treatment for a longer time reduced the amount of the oxide. The heat treatment of the product in an Ar flow also yielded nitrogen containing ceramics, which indicated the effectiveness of nitrogen in the condensation product during the conversion.