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We prepared Tb doped YBO₃ green phosphor by precipitation from a homogeneous solution using urea. Yttrium nitrate, Terbium nitrate, boric acid, urea were dissolved in water. Precipitation reaction from a homogeneous solution was performed by heating the solution at 373 K by water-bath for 1-2 h. pH of the solution gradually rose by hydrolization of urea, then white precipitate was formed. The white precipitate was identified as Y(B(OH)₄)CO₃ by XRD, and SEM observation revealed the shape of the particles were cubic of about 1 µm. Cubic-shaped YBO₃:Tb phosphor was obtained by heating the precipitate at 1073-1278 K.

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The stable colloidal suspension of goethite was consolidated to a bulk by slip casting under a magnetic field of 2 - 12 Tesla. The obtained goethite green body was then sintered at 900-1200 degree centigrade external to the magnetic field, resulting in a topotactic transformation of goethite into hematite. SEM & XRD results show that the transformed bulk hematite was aligned with c-axis along the direction of the magnetic field, which was applied during the slip casting. Magnetic anisotropy increased with the increase of structural anisotropy of bulk hematite.

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Nanoparticles of Ba_1-xSn_xTiO₃ (x=0.00, 0.02, 0.05, 0.10) were prepared by using a microwave assisted solvothermal reaction and a conventional solvothermal reaction under different conditions. The samples were characterized by using TG-DTA, XRD, TEM and EDX. The perovskite phase samples of Ba_1-xSn_xTiO₃ were obtained at 200^oC. The doping of tin(II) in BaTiO₃ resulted in the increase of the amount of OH group incorporated in the lattice and the specific surface area of the sample powder.

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Morphology control is always an attractive field in material synthesis. In this work, titania fibers were synthesized by solvothermal reaction starting from potassium tetratitanate. The reaction temperature was altered from 300 to 400 degree centigrade, and various solvents such as water, methanol and ethanol were used. The phase transformation behaviors were conducted by X-ray powder diffraction analysis and Raman spectroscopy. Morphologies of the smaples were observed through TEM and SEM method. The results revealed that by altering the reaction temperature and solvent, fibrous titanium dioxide with different crystalline phases could be obtained. The photocatalytic activities of the prepared titania fibers were also evaluated.

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It is known that carbon nanotubes (CNTs) with high aspect ratios bundle easily, which can result in agglomeration of the solid particles or flocculation in solution. In other words, good dispersion of CNTs in aqueous or organic solution is not straightforward. This work describes the alignment behavior of CNTs in strong magnetic field and the colloidal processing of CNTs in aqueous systems. A strong magnetic field of 12 T was also applied to the suspensions to control the alignment of the CNTs. The degree of dispersion was found to depend on the properties of the CNTs, pH, Zeta potential level and size of CNTs. In addition, the well-aligned CNTs according to direction of magnetic field were obtained under strong magnetic field.

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We have succeeded in synthesizing metal folding ceramic (SiC) nano-fiber from Si-based precursor polymers using Single Particle Nanofabrication Technique (SPNT). Si-based polymers were cross-linked along ion tracks of nano-size in diameter through the whole thickness of polymer thin film. Nano-fiber was developed on the surface of the substrate by dissolution and washing away of uncross-linked polymer by solvent. Subsequent pyrolysis converted polymeric into inorganic SiC nano fibers. The diameter of nano fiber was depended on LET (liner energy transfer), molecular weight and cross-linking efficiency of polymers.

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Recently, magnetic sensor materials have been widely used in various applications, and further improvements of their properties such as sensibility and chemical durability are required. As new magnetic materials, Co doped TiO2 has been reported to show ferromagnetism. Additionally, the stable immiscibility region exists in both TiO2-SiO2 and CoO-SiO2 binary systems. Therefore, the crystallization of phase separated glass in CoO-TiO2-SiO2 system enables to fabricate the micro-nano composite which consists of Co doped TiO2 ferromagnetic phase in SiO2 rich glass matrix. This composite is expected to show high thermal and chemical durability due to SiO2 rich glass phase. In this study, the phase separated glasses and glass ceramics in CoO-TiO2-SiO2 system were prepared by melt-quenching process. The crystalline phase, microstructure, electric and magnetic properties were examined.

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In this study, the attractive force between nanoparticles in suspension was increased by "entropy bridging", resulting in well-controlled gel state. The prepared nanoparticle gels showed enough yield stress for direct writing.

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Chemical synthesis of ceramic-based materials via organic/inorganic hybrid materials is an attractive method which can offer opportunities to synthesize various kinds of materials such as functional organic/inorganic hybrids, Si-based non-oxide ceramics, thermally stable amorphous ceramic materials, and micro-/meso-porous materials. The microstructure and the chemical composition of the resulting materials can be well controlled at nanometer-scale level and molecular-scale level, respectively, by controlling chemical structure of starting precursor molecules and several high-temperature reactions during the precursor/ceramics conversion process. At the presentation, some recent research works on the chemical synthesis of polymer-derived Si-based non-oxide polycrystalline ceramics, thermally stable amorphous ceramics, and micro-/meso-porous ceramic thin film for gas separation will be briefly reviewed and discussed from a view point to develop novel ceramic-based materials.

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Porous glasses with a few nanometer pores were prepared utilizing a spinodal-type phase separation, and the surface of which was modified by using alkanethiol based silane coupling agents ((CH3O)3Si(CH2)nSH, n=1, 3, 6, 10) via toluene reflex. The obtained thiol-modified samples were oxidized with H2O2 to obtain –SO2(OH) groups. The amount of the introduced silane coupling agents and those reactivity with H2O2 inside the nanopores drastically changed by changing the length of the alkyl chain (n). The structures and charge distributions of the silane coupling agents on the pores were calculated based on the density functional theory (DFT) and DVXa. Proton conductivities of the obtained porous glasses are discussed in relation to the reactivity of the silane coupling agents.

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