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Single crystals of layered titanate K0.8MxTi2-xO4(M=Fe, Co) were synthesized by flux method. When these samples were reacted with 2-dimethylaminoethanol, sol-like precipitations arose. As a result of optical microscope observation, it was observed these precipitations swelled several dozen times as large as original thickness. The swelling samples shrinked rapidly by addition of acid solution or alcohol, returning original plate-like crystals.

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Electrophoresis deposition (EPD) is an effective way to fabricate dense film rapidly without any pressure. In this study, formation mechanism of thin film of layered silicate using EPD method was investigated with different voltage and slurry concentration. From cross-sectional image, the thickness increased in proportion to voltage and exfoliated silicate stuck perpendicular to the electrode surface. Relationship between particle dispersion stability and film formation mechanism was discussed using in situ solidification technique.

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Mechanochemical synthesis of complex oxide was investigated using an attrition type mill. The mill gave strong mechanical forces such as compression and shear stress onto particles with no media balls. When a mixture of BaCO₃ (50nm) and TiO₂ (7nm) was treated, the single phase of BaTiO₃ was identified by the X-ray diffraction pattern of the powder treated in 15minutes.

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In this study, both methyl-groups and h-BN particles were incorporated to modify the structure of the coatings to obtain a thick and creak-free coating. h-BN dispersed silica based hybrid sols were prepared from tetraethylorhosilicate (TEOS), methyltriethoysilicate (MTOS) and trimethylborate (TMB) with acid-catalysis process. The obtained h-BN dispersed sol were dip-coated on polished stainless steel substrates and annealed at 500oC for 1hr in air. Thick and crack-free coatings were obtained from h-BN dispersed silica based hybrid sol composition (h-BN50vol%+hybrid borosilicate(B2O3 30mol%)).

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Polymeric precursors having Ti/Si ratios ranging from 0.001 to 0.1 were synthesized by chemical modification of commercially available perhydropolysilazane (PHPS) with Ti(N(CH₃)₂)₄. Amorphous Si-Ti-N ceramics were synthesized by pyrolysis of the precursor in Ar. The results of XRD analysis showed that the crystallization of alpha-Si₃N₄ from the Si-Ti-N materials with the Ti/Si ratios ranging from 0.001 to 0.01 started at 1273 K. This crystallization temperature was 200 K lower than that of the PHPS-derived Ti-free amorphous Si-N material. FT-IR and ²⁹Si MAS NMR spectroscopic analyses revealed that, during the polymer/ceramics conversion process, the dehydrogenation reactions of the PHPS were apparently accelerated by the chemical modification using very small amount of Ti(N(CH₃)₂)₄. This could lead to enhancing the lower temperature formation of SiN₄ tetrahedral units necessary for the crystallization of alpha-Si₃N₄ at 1273 K.

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Nano-sized aluminum nitride (AlN) particles of 10-20nm in size was synthesized by carbothermal reduction and nitridation of nano-sized mixture of Al2O3/C with NH3 gas. Nano-sized Al2O3/C mixture was obtained by heating an aluminum oleate emulsion at 600oC in Ar gas. TEM observation indicated that nano-sized alumina was homogeneously dispersed in a matrix of amorphous carbon. The XRD, 27Al MAS NMR and FT-IR results showed that a single phase of AlN can be fabricated at as low as 1150oC for 180 min. It was found that nano-sized alumina homogeneously dispersed in a matrix of amorphous carbon was nitrided to AlN at very low temperatures (1150-1200oC).

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Synthesis of carbide powders by pyrolyzing precursors derived from alkoxide

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The preceramic polymer derived Si-C-O ceramic was fabricated via pyrolysis. The specific surface area could be controlled by the process factor such as pyrolysis temperature and amount and type of filler.

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We have succeeded in synthesizing the silicon carbide (SiC) nanowires from polycarbosilane (PCS) using MeV-order heavy-ion beam irradiation technique. PCS was crosslinked along ion tracks of nano-size in diameter through the whole thickness of PCS thin film. Nanowires were developed on the surface of the substrate by dissolution and washing away of uncrosslinked polymer by solvent. Subsequent pyrolysis converted polymeric into inorganic SiC nanowires. The diameter of nanowires was depended on LET (liner energy transfer), molecular weight and cross-linking efficiency of PCS.

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We have found that new Al:Ti(1:1)nanocrystallites are formed in Al₂O₃-TiO₂ gels, and ZrTiO₄ are formed in ZrO2-TiO2 gel by mechanical milling. In this work, copolymerized, amorphous oxide gels were mechanically milled under various conditions. Crystallites formed in the gels were characterized using XRD and compared with those generated in the gels by heat treatment.

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The preparation of ceramics by precursor method will be presented. Acetoacetato complexes of metals were subjected to the reaction with triethanolamine to form polymeric materials, which were converted to oxide-ceramics by molding and pyrolysis. The preparation of oxide superconductors and ferroelectric materials will be presented.

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Novel silica-based hybrid materials were synthesized from three types of building blocks consisting of cage-type organosiloxane derivatives containing mono-, di-, and tri-alkoxysilyl groups at all the corners. The building blocks were synthesized by silylation of a cage-like oligomer with corresponding alkoxychlorosilanes ((RO)_nMe_3-nSiCl). The structure and morphology of gels, which were obtained by hydrolysis and polycondensation under acidic conditions, vary greatly depending on the number of alkoxy groups. Furthermore, nonionic surfactants were used as the structure directing agents to produce mesostructured hybrid materials.

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I summarize our recent achievements that the various inorganic polymers have been used for complex 3D nano/micrometer-sized ceramic structures as well as ordered porous or tubular ceramic structures via lithographic techniques and nanocasting routes. Moreover, we will show the fabricating route of the polysilazane glass derived microfluidics with optical transparency, biocompatibility, thermal stability and chemical inertness. And also high temperature ceramic reactor was fabricated by soft lithography and sacrificial templates, then used as a H2 reformer of fuel cell. In addition, a hydrophilic nanofluidic system was fabricated with newly synthesized organic-inorganic material with excellent patternability. And it is believed that these paved a variety of applications in the fields of tribological MEMS and chemical resistant microfluidics.

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Metal-organic precursor-derived novel nanoparticle-dispersed amorphous silica membranes have been synthesized on an anodic alumina porous support. As our initial study, Ni-doped amorphous silica system was selected and investigated. TEM observation revealed that a crack-free thin layer with a thickness of about 400 nm was homogeneously deposited on the porous support, and Ni-nanoparticles with a diameter of about 5 to 10 nm were found to be located mainly at the membrane surface layer. The nanocomposite membrane exhibited H2 permeance of 1.3x10-7 [mol•m-2•sec-1•Pa-1] at 773 K, and the permeability ratios of H2/CO2 and H2/He were measured to be 89 and 5, respectively.

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