[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

We succeeded in making the porous charcoal compound TiO2. The titania powder, the binder, and charcoal were physically mixed. Afterwards, charcoal was selectively evaporated because it sintered by different atmosphere (oxidation and reduction) and it succeeded in making it to the porous quality. The crystallinity and surface morphology of the samples were observed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Characterization of the photocatalytic properties was performed by measuring the concentration change of methylene blue (wet methylene blue method). The decomposition characteristic of the charcoal compound TiO2 has improved by making it to the porous quality.

View full abstract

Single crystals of Fe-,Co-,Mg-substituted layered titanate have been synthesized by flux method and have been delaminated into the unilamellar nanosheets. Reaction with aqueous tetrabutylammonium ions yielded a colloidal suspension and XRD analysis on the samples confirmed the complete exfoliation. These nanosheets were about 1 nanometer in thickness and 10 micrometer in lateral size as revealed by AFM and TEM.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Two-dimensional periodic arrays of a titania-organic hybrid material, which is derived from the sol-gel method, are fabricated by the multi-beam laser interference technique. Four or two pillars are gathering on the top; "top-gathering pillars", by changing the height of pillars or laser irradiation energy and the top-gathering pillars arrange periodically by the self-organization. The top-gathering phenomena are caused by the capillary force during the drying process.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Electronic substrates mounting active and passive components are essential for increasing the performance of various electronic products. The circuit board is composed of insulating layer and conducting layer. It is regarded as the hybrid structure consisting of ceramics and metal. LTCC developed for the circuit board of high-speed computer in 1990 had excellent performance beyond HTCC previously developed. Lately, according to the demand of low-cost and miniaturization of the circuit board for mobile electronic products, the circuit boards embedding passive components have been developed actively. This talk will explain the aerosol deposition: key technology for the future embedded circuit board and LTCC technology.

View full abstract

In this talk, importance of chemical processing for hybrids and/or thick- and thin- films is emphasized. For example, a thick-film hybrid circuit can be described as a small, self-contained electronic circuit (module). "Hybrid" means that the circuit elements are made by two or more different technologies of thin and/or thick-film technology on substrates. On this so-called thin or thick-film circuit, different types of discrete electronic components can be added using various mounting techniques. Thick- or thin-film technology is also one of the important technologies for manufacturing sensors and transducers. For these applications the technology is used in two ways: to produce the sensor elements and/or to produce the electronic circuits for signal processing.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Recently, much attention has been paid to various kinds of organic-inorganic hybrid materials because of their optical, mechanical, thermal properties. Up to now, we have successfully prepared poly(phenylsilsesquioxane) particles, one of the organic-inorganic hybrid materials, by the sol-gel method. The poly(phenylsilsesquioxane) particles showed glass transition temperature, and the particles were thermally softened when they were heated at temperatures above glass transition temperature. In this work, thermal behavior of poly(phenylsilsesquioxane) particles was investigated by changing the preparation procedure and the amount of solvent that was used.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Well-dispersed Y2O3:Eu nanocrystals with size less than 10 nm can be synthesized by a simple organometallic route. Two strong emission peaks located between 610 and 630 nm, and near 2% quantum yield can be achieved under 466 nm excitation. Excellent dispersibility and long emission life time would be a allow Y2O3:Eu nanocrystals to used as biological labeling. In addition, Y2O3:Eu nanodisks are obtainable under different experimental conditions, which may find some applications in future nano-devices.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Two types of NASICON-based NO₂ sensors were fabricated by combining NASICON disk with two kinds of sensing electrode materials, such as (ITO, NaNO₂) and (ITO, NaNO₂-Li₂CO₃), and their NO₂ sensing properties investigated under the wet conditions at 30 ºC. The NO₂ sensitivity of the (ITO, NaNO₂)-attached device became large with increasing relative humidity below 30 %RH, whereas the NO₂ sensitivity decreased in the range of 30 - 50 %RH. In addition, the EMF at a fixed NO₂ concentration (1.9 ppm) shifted it upward with the change of relative humidity. On the other hand, the (ITO, NaNO₂-Li₂CO₃)-attached device did not almost interfered with water vapor.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

SnO₂-based gas sensors are widely used for gas leakage alarm, CO detector and so on. Recently these gas sensors are being developed also under extreme situation. We reported that CO gas sensor based on SnO₂ responds reversely to small amount of CO, meaning that the electrical resistance of element increases although it usually decreases, when it is operated under lower humid condition. In this study, we aimed to investigate the conditions for which the CO gas sensor gives rise to "reverse response", and to propose the mechanism of "reverse response".

View full abstract

Integrated sensor systems can realize many kinds of new functions for various sensing applications. However, usual silicon devices can not be operated under high temperature environments over 125~150ºC. Temperature tolerant smart micro sensing system has been demanded in various application fields for reliable control system operated over a high temperature range. In this study, temperature stabilized micro accelerometer and leak-compensated precision autozeroed operational amplifier have been investigated for high temperature smart sensing system using SOI (Silicon On Insulator) technology. Integrating SOI sensors and processing circuits with the technology developed, precision smart microsensor systems with high temperature stability can be realized in a microchip configuration.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

An intelligent sensor which can identify a gas species attracts recent, increasing interest. The dynamic response originates from the ambient gas under the transient temperature condition. The dynamic response was investigated with several types of SnO₂ gas sensors fabricated by the electrospray pyrolysis method. The characteristic peak due to the ambient gas arose in the dynamic sensitivity and the dynamic response was closely related to the reactivity with the gas at a temperature. Catalysis, layer thickness and electrode material affected the dynamic response.

View full abstract

[in Japanese]

View full abstract

--We have successfully microfabricated a thick metal oxide films onto the predefined sites on glass, silicon wafer, and polymeric sheet through a monolayer-template-patterning (MTP) technique in aqueous media. Hydrophobic self-assembled monolayers (SAMs), i.e., fluoroalkylsilane or alkylsilane molecules, were used to fabricate the high-quality SAM templates on each substrate. Particulate tin oxide films were deposited from tin chloride aqueous solution. In this study, polyimide (PI) sheet was employed. Ultrathin SiOx layer, i.e., Oxide nanoskin (ONS), was previously formed onto the PI substrate to achieve good adherence between the metal oxide film and the PI surface. Photolithographically micropatterned hydrophobic-SAM layer on the ONS was used as an ultrathin molecular template. Although the metal oxide film was homogeneously deposited onto entire surface of the template, the deposits on the SAM-covered regions were completely eliminated by solution lithography using absolute toluene, resulting in the formation of the well-defined microstructures of the metal oxide.

View full abstract

In this study, the dispersion behaviors of the nano sized ZnO suspension was investigated by the consideration of electrostatic stabilization with organic solvent. The coagulation behaviors was also examined by changing particle number contration, applied forces, distance between electrode and deposition time. The thin film with uniform microstructure was prepared at the condition of the number concentration as ten to thirteen order, DC 5V, 1.5cm, 15 minutes respectively.The dense ZnO thin film with 0.4 micrometer thickness prepared at the condition of the 1050 degree centigrade for two hours soaking.

View full abstract

In order to control the orientation of functional ceramic thin film, we developed a new process using ceramic nano sheet. The highly oriented perovskite compounds such as PZT, LaNiO3 can be prepared even on glass substrate. The experimental details and the electric properties of these films are also discussed.

View full abstract

We have attempted to develop new methodology based upon bio-inspired processing to easily fabricate ceramic micropatterns of high quality. Our method employs organic self-assembled monolayers formed on solid substrates. They are used as templates to control site-selective deposition processes in solutions through various interactions at organic/inorganic interfaces.

View full abstract

Chemical Strategies for Controlling Structural Evolution and Properties of Self-Assembled Organic-Inorganic Nanohybrids

View full abstract

Complex of multiple metal alkoxides are impressive precursors for functional ceramic films and also micropatterns. Bonds of heterogeneous metals via oxygen can be formed in the solutions containing some mono metal alkoxides and affect the following reactions such as hydrolysis and polycondensation. Configuration of the metals and oxygen of the complex is considered to be important for control of development of crystal structures. Therefore, the fabrication using complex alkoxides as sorts of a smallest units of target structures is addressed as a bottom-up processing. In the presentation, we will discuss fabrication of the Pb-free piezoelectric films and micropatterns using several chemically-designed complex alkoxides. The precursor chemistry of the precursors was investigated as well as the crystal structure, microstructure and electrical properties of the resulting piezoelectric structures.

View full abstract

For VO₂-based sensors applicable to temperature measurements, optical disk materials and thermochromic windows by the nature of semiconductor to metal, highly orientated V₂O₅ thin films were prepared by inorganic sol-gel method and spin coating on Al₂O₃ substrate. The inorganic sol-gel technique is easier and cheaper than the alkoxide method as expensive precursors and the need to coat in a dry atmosphere are eliminated. Rutile VO₂ thin film undergoes an abrupt semiconductor-metal transition around 68oC from the high temperature tetragonal phase to a low temperature monoclinic form, which is accompanied by a large change in electrical and optical properties. Spin coating was performed in air, the film was then dried on hot plate. The film was heat treated directly under a reducing gas flow(N₂ and H₂). The thin films of V₂O₅ were found converting to VO₂ thin film under a temperature above 350^oC and in reduction atmosphere. VO₂ thin films were reduced from V₂O₅ via complex compounds. The heat treated films were analysed by XRD and FE-SEM, and electric resistivity measurement. Resistivity was measured with 0.1^oC/min of temperature increasing rate in the range from room temperature to 100^oC. The transition temperature and electrical properties was investigated with adding WO₃. The pure VO₂ polycrystalline thin film with the resistivity change larger than 4 orders through the transition temperature was obtained. With increasing WO₃ contents, transition temperature decreases and jumping order was reduced to 2 orders.

View full abstract

Organosiloxane-based organic/inorganic hybrid materials, which are synthesized using organoalkoxysilanes as a precursor of organic components, have a potential for providing numerous applications. The incorporation of various inorganic components other than siloxane into the organosiloxane structure is further expected to cause a wide variety of properties that arise from the large difference in electron-configuration and coordination number between silicon and other metallic elements. The inorganic components were incorporated into the organosiloxane structure by using metal alkoxides as a precursor. By incorporating an inorganic component, the strength, refractive index and thermal stability were improved and the solid acid/base property was controlled.

View full abstract

High proton conducting P2O5-SiO2-TiO2 glasses were prepared by sol-gel method. Structural analysis were carried out using X-ray, FTIR spectroscopy, thermal stability, pore properties and proton conductivity. The X-ray diffraction spectra indicated that the non-crystalline phase of P2O5-SiO2-TiO2 glasses. Formation of Si-O-Si, P-O-Ti and Si-O-P bonds observed from FTIR spectra for the glass powder. The conductivity of P2O5-SiO2-TiO2 glasses were found in the range of 10-2 to 10-3 cm-1 in humidity (30 to 90 %) and temperature (30 to 90 degree celcius) conditions. A low temperature H2/O2 fuel cell based on glass as an electrolyte was realized. The electrochemical activity was investigated by polarization curves and open circuit voltage. An output power density of approximately 8 mW/cm2 was obtained at 30 degree celcius with relative humidity and 1 atm. The cell performance is mainly determined by the high conductivity characteristics of the electrolyte with modified electrodeKeywords: Sol-gel, TiO2, proton conductivity, power density

View full abstract

Transparent and colorless Sm3+-doped 10Al2O3-5B2O3-85SiO2 glasses were prepared by sol-gel method. The strong absorption band at about 200 nm and weak absorption bands in the range from 320 to 450 nm before the irradiation are assigned to the charge transfer and the 4f-4f transitions of the Sm3+ ions. After irradiation, the increase of the absorption in the range from the UV to visible region is associated with the formation of defect and Sm2+ ions. The emission spectrum of the glass under 337 nm N2 laser excitation before irradiation consists of the four bands coming from 4G5/2-6H5/2, 6H7/2, 6H9/2, 6H11/2 transitions of the Sm3+ ions, respectively. After irradiation, the emission spectrum under the same excitation condition shows the stronger emission band at about 686 nm assigned to the 5D0-7F0 transition of the Sm2+ ions and the weaker bands of the Sm3+ emission. These results reveal that some Sm3+ ions were reduced to Sm2+ ions via femtosecond laser irradiation. The emission band of the Sm2+ ions by photo-induced show red shift, compared with the emission of the Sm2+ by reduction with H2 gas. The mechanism of the photo-induced reduction of Sm3+ ions is discussed based on optical properties.

View full abstract

Nanohybrids consisting of one or more nanocrystalline ceramic phases in an appropriate polymer matrix represent a new class of potentially important functional materials for a number of applications. While most of the existing synthesis routes for such nanohybrids lead to a lack in both the crystallinity of the ceramic nanophases and uniformity in the inorganic-organic nanostructures, we have successfully devised a new, novel templating synthesis route, where block copolymers are employed as the building blocks. In the di/tri-block copolymer templating, the hydrophilic and hydrophobic structural segments of the block copolymers are effectively used as the building blocks for inorganic and organic structural units in the resultant nanohybrids. By controlling the processing parameters involved in block copolymer templating, several uniquely ordered structures have been successfully realized, where the nanocrystalline oxide particles of 3 to 5 nm in sizes can be assembled in the hexagonal, cubical and lamellar hierarchical structures. To remarkably enhance the nanocrystallinity of ceramic phases, such as TiO2, in the hierarchical structures, post-treatments with water vapor at relatively low temperatures have been devised, where the flexible Ti-O-Ti bonds were rearranged leading to the much enhanced crystallization for the TiO2 nanoparticles. These nanohybrids demonstrate much enhanced linear and nonlinear optical responses, as a result of the enhancement in nanocrystallinity of the ceramic phase and the well controlled nanostructural configurations.

View full abstract

Fundamental understanding on stress evolution is lacking for gel-derived coating films although it causes crack formation in films. Especially stress evolution occurring on gel film densification via heating is cruicial for macroscopic cracking that is often accompanied by delamination. In the present study, in situ stress measurement was conducted on alkoxide-derived thin films during heating in order to clarify the effect of various processing parameters on stress evolution. The parameters include water-to-alkoxide ratio, heating rate, chelating agents, organic polymers and CH₃Si(OC₂H₅)₄.

View full abstract

We report some key findings of recent research in silica membrane technology addressing one of the major technology hurdles, hydrostability. Silica molecular sieve membranes exhibit promising properties and separate performance that would find wide applications for hydrogen purification, carbon dioxide capture from flue gases, and other gas separation processes. However, despite the ever growing interest in silica molecular sieve membranes, there is a major technical challenge, that is silica is not resistant to steam which is the case in most of the application processes. Our work in collaboration with Johnson Matthey Fuel Cells in England, has led us to develop a hydrostable material solution to this major problem. We have developed and demonstrated successfully the effectiveness of a new technique to make silica molecular sieve membranes hydrostable. The new technique using carbon templating not only gave rise to silica membranes hydrostability without compromising the separation performance, but was also renders the membrane hydrophilic which is important for hydrogen purification in the presence of water vapour. This new technique involves the use of a hydrophobic organic template,to inhibit surface degradation. Carbonizing the organic template allows for the membranes to attain hydrophilicity and hydrostability.

View full abstract