The laminated or mixed films of SiAlON phosphors were prepared on ITO glasses by electrophoretic deposition (EPD). Three types of SiAlON phosphors, Eu doped Ca-α-SiAlON, β-SiAlON and CaAlSiN₃, which emit the lights of yellow (λ = 585 nm), green (540 nm) and red (620 nm), respectively, were used for the color tuning. The photoluminescence (PL) properties of the laminated or mixed films were characterized by blue-light (λ = 450 nm) irradiation through the ITO glass substrates. The effects of the lamination or mixture of the phosphors are characterized by the broadness of the PL spectra.

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In this study, the effects of several underlayers (Cu, Co, Ag and Fe) on the thin structure of TiO₂ by RF magnetron sputtering were studied and compared. The results of X-ray diffraction (XRD) revealed that the Cu and Ag underlayer worsened the crystal quality of the TiO₂ films. When the Fe underlayer was used, fabricated TiO₂ film showed a mixture of rutile and anatase. The Co underlayer, on the other hand, induced TiO₂ anatase polycrystalline structure. This study also compared the surfactant effect of a Ag layer on the TiO₂ film structure. The results of XRD, X-ray photoelectron spectroscopy, and atomic force microscopy revealed that the Ag layer works as an effective surfactant for reducing the surface roughness and the rutile growth of TiO₂ film on the Fe underlayer.

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Joining of silicon nitride parts by a silicon nitride joint without mechanical pressure was attempted. Reaction-bonded silicon nitride (RBSN) parts were joined using a silicon slurry by a slip-cast technique, followed by reaction bonding and post-sintering. The sintering process changed the original RBSN parts and the consolidated silicon slurry to dense silicon nitride. The joined silicon nitride was successfully obtained and it exhibited an average strength of 404 MPa. Therefore, this technique has the potential to produce strong joints.

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In the present work, four aluminum sources (Al/AlN/Al₂O₃/Al(OH)₃) were used to fabricate mullite-bonded porous SiC ceramics via reaction sintering in air at 1450°C and 1550°C for 1-6 h duration, and the role of aluminum source on microstructure and strength was estimated. The microstructures revealed a variation in necking and adhesion characteristics of SiC/mullite/silica grains. The porosity decreased and strength increased with sintering temperature or time for all specimens, except for the one prepared with Al₂O₃. Amongst the investigated, SiC ceramics prepared with Al₂O₃ exhibited the lowest porosity of 17% and highest specific strength of 19 kN.m/kg, while the usage of AlN rendered a combination of the highest porosity of 42% and lowest specific strength of 5 kN.m/kg. An attempt has been made to qualitatively explain the strength variation of prepared ceramics on the basis of contributing oxidation reactions towards mullitization.

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It was early shown that Ti metal spontaneously bonds to living bone through an apatite layer formed on its surface in the living body, when it was subjected to NaOH and heat treatment to form a sodium titanate on its surface. This kind of bioactive Ti metal was applied to artificial hip joint and already clinically used in Japan. During the study of fabrication process of the hip joint, it was found that sodium content of the surface layer of the Ti metal is largely varied with washing condition after the NaOH treatment, and that apatite-forming ability of the NaOH- and heat-treated Ti metal is liable to decrease in humid environment for a long period. In the present study, the sodium content of the surface layer of the Ti metal was systematically changed by water or HCl treatment after NaOH treatment. Effect of the sodium content of the surface layer on apatite-forming ability in a simulated body fluid and its stability in humid environment of the NaOH- and heat-treated Ti metal were investigated. As a result, it was found that the NaOH- and heat-treated Ti metal gives high and stable apatite-forming ability, when the Ti metal was treated with water after the NaOH treatment to remove partially sodium ions in the surface layer, and subjected to heat treatment.

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Silver-glass composite powders were directly prepared by spray pyrolysis at various preparation conditions. The composite powders prepared at temperatures between 1000 and 1200°C had spherical shape and non-aggregation characteristics when the flow rate of the carrier gas was 20 L/min. The optimum flow rate of the carrier gas to prepare the composite powders with high sinterability and low resistivity was 20 L/min when the preparation temperature of the composite powders was 1100°C. The thicknesses of the conducting layers formed from the composite powders prepared at temperatures of 900, 1000, 1100 and 1200°C were 5.9, 4.5, 3.4 and 4.0 μm at a firing temperature of 400°C. The conducting layers obtained from the composite powders prepared at 1000, 1100 and 1200°C had low specific resistances below 5 μΩ cm even at a low firing temperature of 400°C. The specific resistances of the conducting layers formed from the composite powders prepared at 1100°C were decreased from 3.3 to 1.9 μΩ cm when the firing temperatures were increased from 400 to 550°C.

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Copper indium disulfide (CIS)-based solar cells with titanium dioxide (TiO₂) were produced on F-doped SnO₂ (FTO) by a spin-coating method. The effect of the stacking sequence of the CIS and TiO₂ layers on the electronic properties of the solar cells was investigated. A device based on an FTO/CIS/TiO₂ structure provided better cell performance compared to that based on an FTO/TiO₂/CIS structure. The microstructure of TiO₂/CIS was examined using energy dispersive X-ray analysis, X-ray diffraction, and transmission electron microscopy, and the TiO₂/CIS solar cells provided bulk heterojunction structures. The energy levels of the present solar cells are also discussed.

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Porous calcium phosphate cements (CPCs) were fabricated using gelatin granules as the porogen. As the amount of gelatin was increased from 0 to 43 vol%, the porosity notably increased from 3 to 47 vol%, while the compressive strength decreased from 23 to 14 MPa; however, these values are still expected to be reasonably high for applications in bone tissue engineering. In addition, osteoblastic cells grew favorably on the surfaces of the CPCs prepared using gelatin of 11 and 43 vol%, which contained well interconnected pores with a size of several hundreds of microns, indicating excellent biocompatibility of the porous CPC samples produced in this study.

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A layered ternary carbide Ti₃AlC₂ was synthesized by pressureless calcining process from the mixture of titanium, aluminum and graphite powders. Almost single-phase Ti₃AlC₂ was obtained after calcining at 1400°C for 4 h. The microstructural evolution during the formation of Ti₃AlC₂ was examined at the temperature from 900°C to 1400°C. Ti₃AlC₂ was formed through an intermediate carbide of Ti₃AlC, which was seldom reported in previous literatures. Based on the results of X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS), a possible reaction mechanism was proposed to explain the formation of Ti₃AlC₂.

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In the current work, we investigate the photo-induced hydrophilicity of SrTiO₃ thin films prepared by the sol-gel process. The SrTiO₃ thin films were prepared with different grain sizes but the same crystalline phase, almost the same crystallinity and band gap. With increasing heated temperature, the grain sizes on the film surfaces increased and became more heterogeneous microstructure. Fraction of methylene blue (MB) decomposed on the films was almost the same under UV-A or UV-B light irradiation. Although the films did not show highly photo-induced hydrophilic conversion under UV-A light irradiation, they exhibited the photo-induced hydrophilicity under UV-B light irradiation. The films with smaller grains were highly hydrophilic and higher hydrophilicizing rate than those with larger grains. These results indicate that the SrTiO₃ films exhibited the photo-induced hydrophilicity, and it was affected by the surface microstructure.

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α-LiFeO₂ has been synthesized using Fe₂O₃ and LiNO₃ under various conditions, and the relationship between the CO₂ absorption ability and structural phase transition of the synthesized α-LiFeO₂ has been investigated by X-ray diffraction (XRD) analysis and thermogravimetry and differential thermal analysis (TG-DTA). Mixed powders of Fe₂O₃ and LiNO₃ were heated at 500°C for 5 h to synthesize α-LiFeO₂. The CO₂ absorption reaction of the synthesized α-LiFeO₂ was performed in the temperature range from 200 to 500°C for 2 h under CO₂ gas with a flow rate of 100 ml/min. It was found that the CO₂ absorption ratio of the synthesized α-LiFeO₂ increased with increasing temperature up to 400°C but markedly decreased above 425°C. XRD analysis clarified that α-LiFeO₂ underwent structural phase transition at 425°C, indicating that the structural phase transition suppressed the CO₂ absorption of α-LiFeO₂. Results of the chemical composition analysis suggest that Li defects in LiFeO₂ promote structural phase transition.

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Porous biphasic β-TCP/HA bioceramics were fabricated by sintering of calcined cancellous bovine bone (CBB) treated with different quantities of NH₄H₂PO₄ at various temperatures. The obtained materials had a porous structure (macropores within 200-800 μm and micropores within 1-5 μm) of natural trabecular bones. The specimens were characterized by X-ray diffraction, scanning electron microscopy (SEM), and gravimetric thermal analysis (TG). The results revealed that porous biphasic β-TCP/HA bioceramics were successfully prepared at sintering temperatures within 762°C-829°C. Biological apatite of calcined CBB was found to transform partly into Ca₂P₂O₇ at heating temperatures between 503°C and 762°C. As the ratio NH₄H₂PO₄/calcined-CBB increased, bioceramics with different phase compositions of β-TCP/HA, β-TCP/HA/Ca₂P₂O₇ or β-TCP/Ca₂P₂O₇ were produced after sintering.

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We have fabricated α-TCP porous body (pTCP)/hybrid polymer composites consisting of 2-hydroxyethylmethacrylate (HEMA) and 3-methacryloxypropyltrimethoxysilane (MPS) (pTCP/H). The composites showed an apatite-forming capability in a simulated body fluid (SBF) and a higher compressive strength (57 MPa) than pTCP (0.60 MPa). The compressive strength was still lower than human cortical bone (100-230 MPa). Moreover, there was a problem in that some samples formed cracks after soaking in the SBF due to the swelling of the HEMA-MPS polymer. Compared with HEMA, methylmethacrylate (MMA) does not show any swelling after polymerization, and is expected to have a higher mechanical strength than HEMA. We also fabricated a composite from pTCP and a hybrid polymer consisting of MMA and MPS (pTCP/M). The compressive strength of pTCP/M (94 MPa) was higher than that of pTCP/H before soaking in the SBF. The pTCP/M formed a hydroxyapatite layer in the SBF. The pTCP/M did not form cracks, even after soaking in the SBF. The pTCP/M showed both bioactivity and a high compressive strength. This type of composite has potential for novel bone substitute.

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The epoxy/matrix composites incorporating with dispersed and agglomerated nano-BaTiO₃ fillers were investigated. The relative dielectric constants of the composites with the agglomerated particles were significantly improved, compared to those of the composites with the well-dispersed particles. In addition, the experimental data were in better agreement with the values calculated by the Lichteneker's model than with those of the conventional Maxwell-Garnett's model which has been widely employed for the calculation of the dielectric constant of polymer/filler composites. In order to promote an agglomeration by interlocking between the nanoparticles, the BaTiO₃ powders were heat-treated at various temperatures. An epoxy composite with 40 vol% BaTiO₃ heat-treated at 800°C for 1 h exhibited an excellent relative dielectric constant of 67, along with high polarizability, low dielectric loss, and low leakage current. Similarly, the epoxy composites with agglomerated SrTiO₃ fillers provided a higher dielectric constant than that of their dispersed counterparts. The origin of the increase in the relative dielectric constant achieved by the agglomeration effect is also suggested.

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Boron nitride (BN) nanosheets/polysiloxane composites were fabricated under nano pulse width electric field to enhance the anisotropic alignment of BN nanosheets in a viscous matrix. BN nanosheets have unique physical and thermal properties and exhibit semiconducting behavior with a wide band gap comparing to carbon graphite. However the researches over one dimensional arrangement of BN nanosheets with application of the electric field are limited. The difficulty of modifying the BN surface with electrophilic metal particles or organic functional groups due to its remarkable chemical inertness is one of the reasons. In this study, we attempted to fabricate anisotropic aligned BN nanosheets in a viscous polysiloxane matrix without surface modification of BN nanosheets by using nano pulse width electricity. The electric responses of various nano-dimensional BN nanoparticles were compared by zeta potential. Two kinds of polysiloxane pre-polymers were used to compare the viscosity effects of the polymer matrix. The anisotropic alignment of none-modified BN nanosheets inside polysiloxane can be controlled with variation of the shape and dimension of BN nanosheets, electrodes, DC electric fields, and by application of nano pulse width electricity.

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