Nano crystallization of TiO₂ was observed in a borate-based crystallized glass. The color of the present crystallized glass was changed by the heat-treatment temperature, and XRD patterns of the crystallized glass show that the apparent color change is correlated with the formation of nano TiO₂ crystallites. The local heating technique was used with a XeCl laser to enhance the surface area. The nano crystallite at the surface was observed after laser irradiation, indicating the enhancement of surface area was successfully performed.

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Inorganic-organic hybrid gel films containing TiO2 were prepared by sol-gel process. The films were UV-irradiated through a photomask and then treated with hot-water. Anatase nanocrystals were preferentially precipitated at the UV-irradiated regions. Functionalized micropatterns with different surface-wettability, refractive index as well as photocatalytic activity between UV-irradiated and nonirradiated regions were successfully prepared at temperatures lower than 100 oC.

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Thermal conductivity of glass has not been reported enough below the room temperature. In our previous studies, we measured the thermal conductivities of Na₂O-SiO₂, Na₂O-Cs₂O-SiO₂ and Na₂O-Al₂O₃-SiO₂ glasses in the temperature range from about 130K to r.t, and found that phonon mean free path contributes to the composition and temperature dependence of thermal conductivity in this temperature range. Phonon mean free path is related with glass structure. Therefore, we have discussed the mean free path with the intermediate-range order of glass structure. In this study, we report the conductivity of 20R₂O-80SiO₂ which would have similar structure to each other for different modifier cations.

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Copper was incorporated into borosilicate and soda-lime silicate glasses by a staining method. The staining was performed at 510 to 550oC for various times. In the glasses stained shorter than 48 hours at 550oC, copper ions were present as monovalent. The glasses were colorless in visible region. In fluorescence spetra of the glasses, a broad band was observed at around 500 nm assigned to Cu+. The glasses stained longer than 48 hours at 550oC colored greenish. Broad absorption band was observed at around 800 nm, which is assigned to octahedrally coordinated Cu2+. We will also report the amount of incorporated copper.

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In our previous studies, we have reported the absorption spectra of glass melts doped with cupric ion. In this study, optical absorption spectra of sodium silicate melt doped with iron were measured in the temperature range from room temperature to 1200K and in the wavelength range from 400 to 1000nm by using a specially designed high-temperature spectrophotometer. The peak position around 900nm due to d-d transfer of Fe²⁺ is decreased with temperature below Tg, but it is increased above Tg. The peak height is decreased untill 800K, and above 800K it slightly decreases with increasing the temperature. These changes of optical absorption spectra with temperature is different from the case of cupric ion.

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The luminance of newly developed glass thin films dispersing photoluminescent CdTe nanocrystals (NCs) was evaluated. The luminance of the film is several tens of times bigger than that of the conventional commercial red phosphor (Y2O2S:Eu) when the thickness and excitation wavelength (365 nm) are the same.

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We developed a novel Fabry-Perot interferometer (FFPI) fabricated by glass-ceramic jacketing of single-mode optical fiber. It was demonstrated that the FFPI shows a narrow-band transmission spectrum with no peak splitting. This indicates that birefringence in the FFPI is maintained at the same level as bare optical fiber due to its adhesive-free highly concentric structure. We also developed an atherrmal packaging system for the FFPI that suppresses temperature dependence of the transmission peak wavelength to a level less than one-tenth that of the FFPI without packaging. The FFPI can be applied to narrow-band optical wavelength filters, which enables passive alignment with optical fiber networks without the need for complicated optical connecting systems.

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(60-x)Bi₂O₃-(30+x)B₂O₃-10Li₂O (mol%) glasses were made evaluations on its acid resistance by means of a powder method. The glass powder was treated at 35C for 30minutes in 0.1(mol/l)HCl. In the result, it is found that the acid resistance improves with increasing Bi₂O₃ in the glasses. The reaction product which is analyzed by XRD is only a bismuth oxychloride.

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Pr-doped CaTiO₃ powder samples are synthesized using SiO₂ or B₂O₃ as a flux. The samples showed red emission based on f-f transitions of Pr³⁺ ions by irradiation of light in the wavelength range 250-500 nm. The intensity of excitation spectra and quantum yield below 350 nm increased remarkably with the flux addition.

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The thin films of alkaline-earth stannates with perovskite or layered perovskite structures were grown epitaxially on SrTiO₃ (100) single crystal substrates by pulsed laser deposition. Most of the thin films did not show visible photoluminescence at room temperature in as-grown state. However, after post-annealing treatments at 1000 oC or 1100 oC for 1 h in air, all the films showed intense visible photoluminescence at room temperature as observed in bulk samples. Consequently, the epitaxial thin films, which show several colors including the three primary colors, were obtained in a series of alkaline-earth stannates; Sr₂SnO₄:Ti films for blue, Sr₂SnO₄:Eu-Ti for red, CaSnO₃:Tb-Mg for green, CaSnO₃:Pr for white, and Sr₃Sn₂O₇:Sm for orange.

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Titanate aqueous sols were prepared by mixing titanium isopropoxide and tetramethylammonium hydroxide and then diluting with water. The hydrothermal treatment of the aqueous sols led to the formation of anatase assemblies with asterisk-shape. It is noteworthy that the asterisk-shaped assemblies consisted of anatase with tetragonal crystal system. The purpose of this study is to clarify the reason why the asterisk-shaped anatase assemblies were formed.

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