Series of 0.5% Eu²⁺ activated Ba_2-xSr_xZnS₃:Eu²⁺ phosphor materials were synthesized using polymerzable complex method. The unit cell of Sr doped sample can be identified as orthorhombic belonging to a₂MnS₃ structure type. Sr substitution into Ba site results in the enhanced emission intensity of red light due to the higher internal quantum efficiency and leads to the blue shift of the emission peak to the range with higher human eye sensitivity. The excitation maximum at 450 nm makes this material a prospective phosphor for applications in combination with blue-LED.

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We found that a new fluorescent glass is obtained by sintering porous glass doped with transition metal and/or rare earth metal. In this talk, a review of fluorescent property of the glass prepared by this method is presented as well as its possible applicaion for display.

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We have demonstrated that 30BaO-15TiO₂-30GeO₂-25SiO₂ (BTGS25) glass is a candidate for fiber-type optical devices using crystallization of glass matrix. We determined the composition of glass using substitution of Ge in 30BaO-15TiO₂-55GeO₂ (BTG55) by Si. The BTGS25 satisfied both thermal stability for fiber drawing and electric polarizability for large optical nonlinearity. The BTGS25 crystallized glass showed surface crystallization behavior with the polar c-orientation of fresnoite phase, which is favorable for large second order optical nonlinearity. Using transition metal atom heat-treatment process with a CW-YAG laser, we confirmed clear second harmonic generation from the Cu-doped BTGS25 glass matrix.

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We have reported preparation of the 30BaO-15TiO₂-30GeO₂-25SiO₂ (BTGS25) optic fiber with double clad structure and the crystallization behavior. The composition of the first clad was the BTGS25 with Cu2+ whereas that of the second clad was the BTGS25. We demonstrated that YAG laser irradiation technique is more effective than conventional heating using electric furnaces for preparation of BTGS25 crystallized glass fiber devices.

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Crystallization of glass is a bottom-up type process for material fabrications having a potential for morphology control. We discuss on second-order optical nonlinearities and fluorescence properties of rare-earth ions in crystallized glasses with various morphologies (nanocrystals, highly oriented crystals, etc.) from the points of asymmetric crystal fields.

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The photoelastic constant(PEC) and compositional dependence of structure of binary SnO-P₂O₅ (SP) glasses with 52-72 SnO mol% were studied. PEC was determined using a frequency stabilized transverse Zeeman laser (STZL) at 633nm. The photoelastic constant (PEC) decreases with increasing SnO concentration. The structure of SP glasses was evaluated by FT/IR and Raman spectroscopy. The water durability was investigated by weight loss and Raman spectroscopy for SP glass samples immersed in distilled water at 30-70^oC. Raman spectra indicated in the immersion test that Q¹ units form and Q² units decrease as a result of water attack upon the phosphate chains with increasing immersion time in 62SnO-38P₂O₅ glass. The relationship between the properties and glass structure with chemical bonding is discussed.

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Macroporous SiC ceramics with porosities ranging from 60% to 85% were fabricated from extruded blends of carbon-filled polysiloxane using expandable microspheres as sacrificial templates. The fabrication process involved the following steps: (i) extrusion and in situ foaming of a mixture of polysiloxane, carbon black (used as a carbon source), Al₂O₃-Y₂O₃ (used as a sintering additive), expandable microspheres (used as sacrificial templates), and SiC (an optional inert filler); (ii) cross-linking the polysiloxane in the extruded blends; (iii) transforming the polysiloxane by pyrolysis into silicon oxycarbide; and (iv) fabricating macroporous SiC ceramics by carbothermal reduction and subsequent sintering. Microstructure and morphology development of SiC grains during sintering was investigated.

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Optimum spark-plasma-sintering processing was examined in order to fabricate transparent spinel polycrystal. For a low heating rate of 10C/min, in-line transmission T of spinel polycrystal depends strongly on sintering temperature, particular in visible-wavelength ranges. For a infrared-wavelength of 2000nm, T(2000) attains 60-70% irrespective of temperature. For a visible-wavelength of 550nm, however, T(550) varies from 2 to 50% depending on sintering temperature; T(550) shows a peak value of about 50% at around 1300C. The temperature dependent in-line transmission can be ascribed to the change in microstructure such as grain size, resultant residual porosity and the precipitation of MgO phase.

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We fabricated transparent silica glass film by sintering a green compact above 1673K and high-vacuum(10-4Pa) atmosphere conditions. Microscale surface modification of silica glass films were. examined by applying conventional stamp mold. The glass green film imprint was proceeded through the simple steps of pressing (~6MPa) at room temperature. The imprinted transparent films were also fabricated by high-vacuum sintering method.

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Perovskite-type oxide fine powders could be prepared by a polymer precursor method. The powder could be utilized in screen print method for preparation of a thick-film for a hydrogen-phosphate ion sensor. The Co and Fe based perovskite-type oxide thick-film device showed good properties of amperometric sensing of the hydrogen-phosphate ion.

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The epitaxial YSZ and gadolinia doped ceria (GDC) thin films were deposited on Si substrate and the residual stresses of the samples with thickness and deposition conditions were calculated. The electrical conductivities of YSZ and GDC thin films with measurement temperature show lower activation energy, 0.39eV for GDC and 0.41eV for YSZ, compared with those of bulk or polycrystalline. It might be possible working at 300 – 350 oC as a new type oxygen sensor.

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Four kinds of NASICON (Na1+xZr2SixP3-xO12, x=1, 1.5, 2 or 2.75) - based CO2 devices were combined with a Li2CO3-BaCO3 (1:2 in molar ratio) auxiliary phase to investigate the relationship between aging treatment and EMF drift. When exposed to 250 ppm CO2 for 200 h at 450 ºC under dry condition, the EMF of each NASICON device decreased with aging time. To research the cause of the EMF drift, a mixture that consists of NASICON and Li2CO3 was heated at 750 ºC in air. From X-ray diffraction measurement, it was confirmed that new crystal phases such as Li2ZrO3, Na2Zr(PO4)2 and Na5Zr(PO4)3 were formed instead of Li2CO3 Na3Zr2Si2PO12, Na3Zr2Si2PO12 and Na2ZrSiO5 phase. This suggests that the EMF drift relates with the formation of new crystal phase at the interface between NASICON and auxiliary phase.

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Optical properties of SnO₂ films were investigated under an operating condition of gas sensors. The films were prepared by a liquid phase deposition method. The films were highly transparent over the visible range. When the films were treated in 0.5 %H₂/N₂, the absorption was enhanced at shorter-wavelength-region from 350 to 500 nm. Such absorption was considered to relate to the defect formation which concerned to the response to the gas.

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Various types of SnO₂-based thin films were fabricated as a gas-sensing film of MEMS sensors by utilizing radio-frequency magnetron sputtering. Pt-sputtering on the SnO₂ film improved responses to both 1000 ppm H₂ and 50 ppm ethanol, while Pd-sputtering on the film showed the reverse tendency, i.e. ineffectiveness in improving the responses. Furthermore, hetero-stacking of a SnO₂ film on the Pt-added SnO₂ film was very effective in enhancing the H₂ response.

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In this study, we have experimentally investigated particle statistics caused by limited number of crystallites satisfying the diffraction condition. A convenient method to analyze particle statistics is presented, and possibilities for application to determination of multiplicity of reflections, evaluation of crystallite size and characterization of malti-phase mixtures are discussed.

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