Photoluminescence properties of TiO2 films obtained by the chemical vapor deposition method have been investigated in the wide temperature region. An intense green emission originated from the self-trapped exciton recombination has been observed at low temperatures under UV laser excitation. Cathodoluminescence of the film shows an additional ultraviolet emission band which appears at high acceleration voltages (> 5 kV). Peak energy of this emission (∼3.35 eV) is in a good agreement with the value of the optical energy band gap of TiO2. Both the green and ultraviolet emissions are discussed in terms of linear coupling configuration coordinate model.

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The whiskers synthesized using a chemical-vapor deposition apparatus show the intense ultraviolet emission induced by electron impact. To evaluate the crystal growth process of ZnO, the relationship between morphology and intensity of the cathodoluminescence of the ZnO whiskers was examined. The ZnO whiskers and the ZnO polycrystalline films were provided for the experiment. The intensity of the ultraviolet emission of the ZnO whiskers was larger than that obtained from the ZnO films. This implies that the intensity of the cathodoluminescence increases, when crystal growvth changes from continuous film growth to whisker growth.

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We fabricated ZnO whiskers which emitted ultraviolet ray at 385 nm by electron impact, on the (100) single crystalline silicon wafer using chemical-vapor deposition apparatus operated under atmosphere. In this study, the incident angle of the electron beam to the whiskers was varied to investigate condition in which the intense cathodoluminescence is obtained. The intensity of the cathodoluminescence increased with the incident angle. 45 incidence was optimum for obtaining the intense emission.

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We have reported the whisker-type cold emitter manufactured by an electrically conductive ZnO:Al whiskers with an extremely sharp tip and an a-CNx:H films as a field emitting material with a low work function. In this study, MgO polycrystalline film was investigated as a field emitting tip material. MgO has a comparatively large secondary electron emission and anti-sputtering characteristic. The field emission of 1.8 mA was obtained at the following conditions: a threshold voltage of 390 V and an applied voltage of 1.8 kV.

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We manufactured a flat display device using whisker-type cold emitter. In this study, luminance of the flat display device was measured using a spectral light meter. The 20×30 mm² red flat display device was provides for the measurement. The luminance of 1250 cd/m² was obtained at a gate voltage of 570 V and an accelerating voltage of 8 kV.

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We have already reported that preferential orientation fluorescent whiskers have high luminescence intensity than that of random oriented polycrystal films. In this study, preferential orientation axis of fluorescence whiskers, <111> or <100> direction was achieved of the cubic structure of the Y₂O₃ whiskers. The relationship between orientation and luminescence intensity was investigated. No difference between the photoluminescence spectrum pattern of <111> and <100> whiskers was seen. The maximum intensity of the 5.5 at.% Eu³⁺<111> Y₂O₃ whiskers was as same as that of the 6.5 at.% Eu³⁺<100> Y₂O₃ whiskers.

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Calcium carbonate crystals were precipitated on a polymerized 10, 12-pentacosadiynoic acid (PDA) film from solution in which [Mg²⁺]/[Ca²⁺] ratio was about 10. Calcite crystals precipitated on the PDA film, and the c-axes in the precipitates were perpendicular to the polymerization direction of the LB film. The regulated features of inorganic/organic interfaces can control the crystallographic directions of inorganic materials. The precipitates grown from the solution containing Sr²⁺ ion were aragonite crystals and they were randomly oriented.

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Ag nanoparticles were prepared by reduction of Ag+ in the presence of stabilizers. AFM-anodization of Si substrate, covered with cationic self-assembled monolayer, formed silicon oxide lines. Fine wire assemblies of Ag nanoparticles were essayed to be prepared by soaking an AFM-anodized Si substrate into a dispersion of cationic Ag nanoparticles. Silanol region was negatively charged in aqueous solution. Thus electrostatic attraction between cationic Ag nanoparticles and silanol region, and electrostatic repulsion between cationic Ag nanoparticles and cationic self-assembled monolayer gave the Ag nanowires.

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Micropatterning of zinc oxide thin film was realized using site-selective deposition which is involved molecule recognition of inorganic-organic .A SAM which has a pattern of both silanol and alkyl surfaces was immersed in an aqueous solution containing Zn precursor. ZnOH was deposited and a thin film was grown on the silanol surface selectively. ZnOH thin film fabricated by site-selective deposition has no cracks and the feature edge acuity of its micropattern was much higher than that of the micropattern obtained by lift-off process. And ZnO thin film was by annealing ZnOH thin film at 300°C.

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Pulse laser deposition(PLD) method is a powerful technique to synthesize the ceramic thin films on various substrates. Especially, in the bioceramics fields, the coating of calcium phosphate based materials is expected to enhance the bioactivity of the metals and ceramics. In the present study, thin coatings of calcium phosphates on various substrates were synthesized by the PLD method at 500°C in O₂ atmosphere. The microstructure of thin calcium phosphate coatings was observed by SEM and TEM.

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A bioactive bone-substitutes with mechanical properties analogous to those of natural bone are strongly desired to be developed. In the present study, PE/ TiO₂ composites were prepared from anatase (TiO₂) nano-powder and polyethylene (PE) with different melting flow rate (MFR) using a batch-kneader. The composite with a uniform distribution of Ti0₂ powder were prepared. The composite prepared from PE of MFR=8 shows the highest bending strength (about 50MPa) and Young' s modulus (about 7GPa) within the range of the mechanical properties of natural bone. The composite formed apatite on its surface in a simulated body fluid within 7 days. Therefore, PE/ TiO₂ composites with such mechanical properties and bioactivity are considered to be useful as bone-repairing materials.

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Two layer glass coatings on Co-Cr implant alloy were prepared using a simple enameling technique. Their glass composition and its optimum condition (temperature and time) were presented in order to fabricate homogeneous coating with good adhesion to the allay. Glass coatings with glass A (49.8SiO2-15.5Na20-4.2K20-15.6CaO-8.9MgO -6.0P2O5 wt%) and glass B (48.4SiO2-14.7Na20-5.2K20-20TiO2-11.7 (RO, R2O3 , RF2) wt%) were fired at 750°C for 2 min in air and showed excellent adhesion. The glass coatings with excellent adhesion to the substrate and to form Hydroxyapatite when immersed in a simulated body fluid (SBF) for 30 days can be fabricated.

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It was reported that a biocomposite scaffold (BcS) was formed on a hydroxyapatite in culture medium with fetal bovine serum, and it had an active effect on cell growth. In this study, BcS was prepared on titanium with alkali-heat treatment to induce a bioactivity. Proliferation and adhesion of osteoblast-like cells were activated on BcS. Consequently, it was suggested that BcS could be used to bioinert material as a cell active substrate and tissue-engineering scaffold.

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Ceramic-polymer biomaterials having excellent apatite-forming ability in simulated body fluid were prepared by hot-pressing a mixture consisting of poly(lactic acid) (PLA) and calcium carbonate (vaterite). When vaterite of 30 wt% was introduced, the modulus of elasticity was effectively improved by 3.5∼6 GPa. The composite formed a bonelike apatite layer on its surface affer soaking in SBF at 37°C even for 1 days. The sponges composed of a skeleton of the vaterite composite or a bonelike apatite composite could be prepared easily. They have large porosities of∼90% with large-sized pores. The sponges may be great potential candidates as bone fillers or scaffolds for tissue engineering.

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Porous hydroxyapatite (HA) ceramics can be regarded as an assembly of small HA units. We are trying to construct porous hydroxyapatite ceramics in bony defect using HA small beads with a through-hole (HA beads). The HA beads were prepared by sintering HA gel-capsules with a through-hole. Osteoconduction in the interconnected through-holes was evaluated by animal tests.

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We investigated surface properties of polarized calcia stabilized Zirconia (CSZ) in simulated body fluid (SBF). CSZ powder was synthesized by sol-gel method. After being heated 800°C for 1h, the CSZ powder was pelletized. The pelletized CSZ was sintered at 1500°C 2h in air. When the CSZ deposited HAp, the CSZ ceramics will expect as new composite biomaterial.

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Hierarchically laminated architecture of calcium phosphate-organic polymer composites was obtained through periodic precipitation in poly (acrylic acid) containing phosphate anions by diffusion of calcium cations. Periodic bands of Ca. 10mm in thick were produced by precipitation reaction between calcium cations and phosphate anions in the polymer gel. Porous hydroxyapatite having a similar layered structure also prepared by calcination of the composites.

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Cytocompatibility of chitosan-organosiloxane hybrids was evaluated due to osteoblastic cell (MG63) adhesion, proliferation and ALP activity. The hybrid showed higher cytocompatibility than chitosan membrane. Biodegradability of the hybrid was also investigated due to reactivity and swelling for phosphate buffer and lysozyme solution. The hybrid showed lower biodegradability than chitosan membrane. Appropriate amount of γ-glycidoxypropyltrimethoxysilane (GPSM) mixed with chitosan affected not only the cytocompatibility but also the biodegradability.

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X-ray photoelectron spectroscopy (XPS) has been applied to the structural analysis of amorphous calcium phosphate (ACP) and for the purpose of comparison also to that of calcium phosphate glasses with compositions 35, 45 and 55 mol% CaO. In the case of the phosphate glasses, from the measurements a discrimination between bridging, non-bridging and double bonded oxygen atoms was possible. In this study, the short-range structure of ACP was discussed.

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Changes in the microstructure of single-crystal apatite fibres as a result of heat treatment were examined using a range of techniques: XRD, FT-IR, SEM and TEM. The as-synthesized fibres were highly strained and comprised domains that were preferentially oriented with the c-axis parallel to the surface of the substrate. When the apatite fibres were heated at 800°C to 1200°C for 1 h, the domain structure disappeared but remained highly strained. The ultrastructure of fibres heated at 1000°C and 1200°C changed during sintering to form some grain boundaries and dislocations. The apatite fibres heated at 1200°C for 1 h contained many voids formed by the release of carbonate groups during sintering.

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To fabricate apatite-polymer hybrids with structures similar to bone tissues, it is important to use a process where bone-like apatite is formed on polymer surface in a body environment. We previously found that apatite could be deposited on the surfaces of aromatic polyamide films containing carboxyl or sulfonic group in a solution mimicking extracellular fluid. In this study, morphology of the apatite formed on the polyamide films containing carboxyl group was examined. Aggregations of minute flakey particles were observed, and the particles formed complex conjunctures at the interface between the apatite layer and polymer surface.

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Mesostructured niobium oxide was synthesized by ion exchange reaction using layered perovskite K₂NbO₃F and C₁₆-alkyltrimethylammonium surfactants and 2d-hexagonal-type K-M-niobium oxides (M=Ca, Sr, Ba) were prepared by ion exchange reaction in MCl₂ aqueous solution. XRD peaks due to existence of mesostructure were observed in the samples calcined at 423K in air. This result suggests that thermal stability of the mesostuructured niobium oxide are improved by addition of alkali earth metal ions.

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Mesoporous silica with hexagonal structure was synthesized by liquid-crystal templating method. The synthesized products showed a narrow pore size distribution at around 2.5nm in pore diameter and the high specific surface areas at around 1200m ²/g. The crystallization kinetics of the mesoporous silica has been studied using differential thermal analysis(DTA). The activation energies of crystal growth obtained from the modified Kissinger-equation are 486kJ/mol and 276kJ/mol for the mesoporous silica with and without surfactant template, respectively. The crystallization kinetics of Mo-containing mesostructured silica was also discussed.

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XPS and NMR were used to study the effect of sulfur and crystallinity on the transformation of Nanoporous alumina membranes prepared by anodic oxidation using sulfuric acid electrolyte. The transformation temperature at ca. 1250°C is influenced by the pore size, presumably due the critical crystallite (domain) size necessary to develop the stable α-Al2O3. NMR results also support that samples with larger pores contain poorly crystalline phases. In XPS study, Ar+ ion etching was performed on the sample to etch the surface at a rate of 3 nm min-1. As a result, sulfur was found to be concentrated within a depth of 3 nm from the surface. The S content of the surface was found to decrease to about one-fourth at a depth of ca 10 nm.

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Macroporous alumina materials were fabricated via colloidal processing using polymer spheres as the template and ceramic particles as the building blocks. The influence of the suspension conditions on the formation of the pore structure has been investigated. The results showed that the suspension conditions have a significant effect on the pore morphology. A well-defined 3-dimensional ordered porous structure with a controllable pore size and porosity could be obtained through the hetero-coagulation self-assembled processing of the polymer/ceramic particles.

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A novel fabrication process for porous alumina-based ceramics was developed using hydraulic inorganic binder (hydraulic alumina) and water. The hydraulic alumina and water acted as agents for direct consolidation, and water acted as a fugitive material to create open pores too. The green bodies formed with the hydraulic alumina and water had low green densities and high compressive strength. Hydraulic properties and sintering of the hydraulic alumina were studied.

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The purpose of this study is to make a porous aluminum oxide film on Nesaglass by anodic oxidation and apply it as functional materials. Aluminum does not strongly adhesion to ITO, so Nesaglass is heated at 300°C for the evaporation. Aluminum evaporated on nesaglass heated at 300°C is anodized under various conditions. It is found that the states of the aluminum oxide film fabricated on nesaglass differ widely by the conditions. Aluminum oxide films with high quality could be fabricated on nesaglass under the condition of 10V and 25°C in 10vol% sulfuric acid aquaeous solution.

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In order to prepare porous ceramics without generating a large amount of CO₂ be decomposition of organic materials contained in the raw material as pore-former, highly porous silica ceramics was prepared by mechanical foaming of silica sol. Since gelation time of silica sol was controllable to desired range by adjusting its pH, temperature and concentration of surfactant, the silica sol foamed mechanically before gelation kept its foam-like-structure after foaming. The porosity of the foamed silica calcined at 600°C was over 90%, and bending strength and young's modulus of the foamed silica heated at 1000°C were 2.4MPa and 0.9GPa, respectively. The permeability, which is important for application to filters, was 5.3 X 10^-11m².

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A novel processing, so-called simultaneous etching method, has been developed for fabrication of mesoporous films with one-dimensional through channels on given porous substrates. One side mirror polished bulk phase-separated glass disk (Vycol glass) was used as the substrate. A precursor film that consisted of needle-like Fe2O3 nano-crystals and SiO2 matrix was formed on the substrate, then the film and the substrate were etched simultaneously. Finally, a silica membrane with mesoporous silica layer with one-dimensional through channels was obtained.

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Adsorption of p-nitroaniline (p-NA) into silicalite-1 (S-1) micropore was examined by XRD, TG-DTA, UV-Vis and IR measurements. Silicalite-1 single crystal adsorbed with p-NA was prepared by heat-treating a mixture of S-1 and p-NA in vacuo. It was found that p-NA molecules adsorbed more preferentially into the pore channel of S-1 than the outer surface of particles. The amounts of p-NA molecules were adsorbed into the pore channel of S-1 strongly suggest that p-NA were adsorbed only at the intersection of the straight channel and zigzag channel of S-1.

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Municipal incinerator fly ash has too much calcium in its component to be converted to zeolite. Zeolite was synthesized from municipal incinerator fly ash by addition of water glass. Water glass and municipal incinerator fly ash were mixed with NaOH solution and hydrothermal synthesis was performed. Zeolite Na-P1 was formed by addition of over 10g of water glass. Increase of reaction temperature and amount of added water glass increased CEC. Maximum of CEC was 243 meq/100g.

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Coal fly ash was converted into various zeolites by alkaline treatment, and wood waste was carbonized and activated by calcination. In this study, the porous material for adsorbent used these industrial wastes was investigated. Coal fly ash and wood waste were kneaded together with appropriate amounts of water and bentonite used as caking additives. After molding this kneaded mixture, it was calcined at 600 or 850°C under N2 atmosphere. Then, the calcined bodies were hydrothermally treated in 2.0 M NaOH aq at 120°C for 20 h. Na-P zeolite species were found in the obtained calcined bodies. This treated material exhibited adsorption properties for methylene blue in liquid phase.

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4-Phenylazobenzoyl chloride or 4-phenylazobenzoic acid was intercalated into interlayer space of kanemite containing surfactants. After extraction of the surfactants in the interlayer space with ethanol, kanemite-azobenzene composites containing physisorbed and chemisorbed species were obtained. Cis-trans photoisomerization of the azobenzene unit existing in the interlayers has been observed under UV irradiation.

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In this study, smectite / LDH composites were prepared using synthetic and natural saponites and co-precipitated layered double hydroxide (Mg-Al-LDH) by stirring in distilled water and dry and wet milling. The XRD peaks of LDH phase in the composites were clearer than that of just mixed sample of saponite and LDH. The wet milled sample had higher specific surface area than the dry milled sample, and this may be caused from re-lamination of saponite layers in these composites.

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From the standpoint of resource recovery, a way to convert industrial wastes including iron compounds into functional materials such as an ion-exchanger and a catalyst has been developed. The authors have successful in syntheses of Zn/Fe or Mg/Fe hydrotalcite-like compounds from the wastes. The resulting products including those hydrotalcite-like compounds showed removal properties for PO₄^3- and/or NO₃^-ions.In the present work, removal-selectivities of the products for PO₄^3- and NO₃^-ions have been investigated, using anion-mixed solutions in which Cl^-, PO₄^3-, NO₃^- and SO₄^2- ions exist.

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Hydroxyapatites are the major inorganic constituents biological hard tissues such as bones and teeth. Furthermore, various ions can exchange with the ions of hydroxyapatite lattice. Therefore, apatite based materials are expected to apply for absorbents of harmful metal ions. In this study, the removal of As ion from geothermal water was attempted. The ability of As ion into hydroxyapatite structure and surface was investigated.

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We have synthesized β-Co(OH)₂ platelet with developed {001} plane (average diameter ∼0.5 μm, aspect ratio ∼5) by the precipitation method. The platelet has a highly anisotropic shape and similar crystal structure with the CoO₂ sublattice of cobaltite thermoelectrics (e.g., Ca₃Co₄O₉). Thus, the prepared β-Co(OH)₂ platelet would be a candidate reactive template (precursor) for the fabrication of the highly textured cobaltite thermoelectrics.

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We prepared highly <001>-textured Ca3Co4O9 ceramics by the reactive templated grain growth (RTGG) method using a CdI2-type structured Co(OH)2 platelet as a reactive template. The Co(OH)2 particles with aspect ratio ∼5 were wet-mixed with a complementary reactant CaCO3 and the particles were uniaxially aligned by tape casting. Upon heat treatment, Ca3Co4O9, or misfit layer structured [Ca2CoO3]0.62[CoO2] was in-situ formed with maintained orientation of Co(OH)2. The analytical investigation revealed that the topotactic conversion from a Co(OH)2 platelet into a platelike Ca3Co4O9 grain through spinel-type Co3O4 phase.

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We fabricated highly <001>-textured Ca3Co4O9 ceramics (Lotgering's orientation degree∼100%) by the reactive templated grain growth (RTGG) method. It was found that in-plane electrical conductivity ∼1.55 X 104 S/m (1050 K) was much higher than those of out-of-plane and non-oriented samples. This suggests that the RTGG method provide the highly textured Ca3Co4O9 ceramics with enhanced thermoelectric properties.

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Ca_2.6Bi_0.4Co₄O₉ thin films with different grain sizes (50 - 500 nm) were prepared by a spin coating method. Films were polycrystalline in nature and oriented preferentially in the (001) direction. Electrical properties were measured to study the effect of grain size on thermoelectric (TE) properties. The film with grain size of about 100 nm has the largest TE power factor. An improvement of TE performance can be obtained by optimizing the grain size.

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Recently, oxide compounds have attracted attention as promising thermoelectric materials because materials with high thermoelectric performance have several problems, such as low melting or decomposition temperatures, harmful or scarce elements. Bi₂Sr₂Co₂O₉ with a layered structure have been prepared using a solid state reaction and their thermoelectric properties were investigated. The compositions of samples are Bi_2-xBa_xSr₂Co₂O₉, Bi₂Sr_2-xBa_xCo₂O₉, and Bi₂Sr₂Co_2-xCu_xO₉.All samples are p-type conductors. These substitutions are effective for decreasing resistivity. The power factor of the Bi₂Sr₂Co_1.95Cu_0.05 is about 1.91μW/K²cm.

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For the purpose of thermoelectric generator using waste heat energy from car exhaust gas, thermoelectric oxide ceramics have been developing structural control in the wide range vision (panoscopic scale) from crystal structure to grain ordering in ceramics as synergistic materials. The results of structural design on the thermoelectric properties of ceramics are shown.

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In the present work, thermoelectric properties of Ca1-xSrxMn3O10, which was layered perovskite Mn-based compounds, in a temperature range of 300 to 800°C have been investigated. Polycrystalline solid solution specimens with single phase were prepared up to x=0.4 in the Ca1-xSrxMn3O10. The solid solutions exhibited the Seebeck coefficient higher than the mother compound, Ca4Mn3O10. The absolute value of the Seebeck coefficient of Ca3.6Sr0.4Mn3O10 at 800°C was around 227 μV/K.

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Thermoelectric(TE) oxide materials have been attracted attention, since it was reported that NaCo₂O₄ had high TE properties. Because layered α-titanate NaCo_0.5Ti_0.5O₂ has the same crystal structure as NaCo₂O₄, which is edge-shared CoO₆, TiO₆-octahedral structure, it is expected to become a new TE material have high properties. In this study, we investigate a possibility of NaCo_0.5Ti_0.5O₂ for a new TE material and effect of metal-ion substitution for A, B-site. Single phase α-NaFeO₂-type titanate of the products formed at 1000°C in air. The values of TE power and electric resistivity decreased with increasing temperature, showing a semiconductor behavior. TE properties were improved by the substitution of Nb for Ti-site.

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Electrical conductivity and Seebeck coefficient of the layered oxyselenide La1-xSrxCuOSe (x = 0.00－0.20) were measured in a temperature range of 373－673 K in a flowing N2 gas. The non-doped LaCuOSe showed the p-type degenerate semiconducting behavior with the conductivities of ∼100 Ω-1cm-1, whereas the Sr-doped materials with x = 0.05－0.20 showed the p-type metallic behavior. Thermoelectric power factors were estimated to be 1.0－1.4×10-4 Wm-1K-2 for the sample with x = 0.05.

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High temperature electrical conductivity and thermoelectric power of amorphous boron and polycrystalline boron phosphide films grown in silica glass by deuterium lamp CVD process were measured to evaluate the thermoelectric figure-of-merit (Z), which was determined by the electrical conductivity of the film, In particular, the Z value for photo-thermal BP films was higher (10-4/K) than boron films, indicating that they are promising for high-temperature thermoelectric materials.

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We have prepared electrodeposited boron wafer by molten salts with KBF4-KF at 680°C with graphite crucible for anode and silicon wafer and nichel plate for cathodeunder various current densities of 1∼2A/cm2. Amorphous p - type boron wafers with purity 87% was deposited on nichel plate for the deposition time of 1h. The temperature dependencies of electrical conductivity showed thermal activated type with activation energy of 0.5eV. Thermoelectric power tended to increase with increasing temperature up to high temperatures with high values of(1∼10)mV/K. Thermoelectric figure of merit showed 10-4∼10-3/K at high temperatures depending on current densities.

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The Li doped NiO thin film was deposited by r.f. sputtering method on three different substrates and followed by thermal annealing. The catalyst Pt thin film is deposited on a half of area of NiO thin film to make a thermoelectric hydrogen sensor. As deposited NiO thin film has amorphous state and Pt thin film on this NiO film has no catalytic activity. On the other hand, thermal annealed NiO thin film has crystallized and Pt thin film on this NiO film shows usual exothermic temperature increase arise from catalytic reaction.

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Novel electrochemical reactors for NOx decomposition were successfully fabricated by nanostructure control of catalyst-electrode layer in the cells. Energy consumption on the cell working was reduced and reached to the applicable revel. High performance thermoelectric ceramics and power cells were developed to supply a part of electrical energy for deNOx cell working by recycling wasted heat in the exhaust gas.

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