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We investigated photoluminescenct(PL) property of silica doped with rare metal under VUV exciation. Tb,Dy,Tm showed relatively strong PL. Intensity of PL inrelation to co-dopant and matrix are investigated.

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In order to evaluate the total energy budget of Er-doped fiber for optical amplifier in telecommunication, the absolute energy spectra of lateral emitting light was accurately measured with an integrating sphere as well as an optical spectrum analyzer. It was found that about 30% of light was scattered or emitted outside the fiber, 40% of the total energy was nonradiatively lost, resulting the power conversion efficiency of about 30%.

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Titania/nitrogen-doped titania nanocomposite was prepared by the following route: Nitogen-doped anatase titania photocatalyst TiO2-xNy was prepared by solvothermal reaction at 190oC for 2 hours by using HMT as nitrogen sources. It was mixed with certain amount of commercial titania in different ratio by milling in liquid acetone using agate mortar. The phase composition, crystallinity, specific surface area, photo chemical properties, and the photocatalytic abilities were characterized. Some of the Titania/TiO2-xNy nano composite materials showed excellent photocatalytic ability for the oxidative destruction of nitrogen monoxide under irradiation of visible-light>510nm and the acetaldehyde decomposition ability under UV light irradiation. This might be due to the TiON acts as the acceptor of photoinduced electrons while TiO2 collects the holes. The recombination of the electron-hole was effectively depressed by the heterogeneous electron transfer.

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We fabricated the crystal line patterns in fresnoite type Ba₂TiGe_xSi_2-xO₈ crystal line patterning by YAG laser irradiation in BaO-TiO₂-GeO₂-SiO₂ glass. We confirmed that the polarization dependences of micro Raman spectra and second harmonic generation in crystal line patterns. It is found that crystallite in the line pattern is highly oriented along to the laser scanning direction.

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Transparent sintered bodies of CaF2, which has very high abbe constant, were made by a colloidal process. The sintered bodies were made through preparation of CaF2 particles by the wet chemical process, pressing with metal-dies, sintering in atmosphere, and HIP treatment in Argon. The refractive index and abbe constant were 1.43 and 95, respectively. The optical constants were equivalent to ones of single crystal of CaF2. The transmittance was lower than the single crystal in the wavelength range of UV, and equivalent in the wavelength range of IR. CaF2 was obtained by the present simple process as well as the conventional method of the single crystal. Eu or Tb ions were doped in the sintered body as activators maintaining the transparency. The application to transparent luminescent materials is expected.

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Fe-substituted titania nanosheets have been synthesized by chemically exfoliating precursor layered titanates into colloidal single sheets. Obtained nanosheets were self-assembled layer-by-layer with polycation onto substrates to produce ultrathin films. Magneto-optical measurements demonstrated that Fe-substituted titania nanosheets acted as ferromagnetic nanomaterials at room temperature, and their multilayer-assemblies exhibited magnetic circular dichroism in the ultraviolet-visible region.

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We here report a novel synthesis method of Au@TiO2 core-shell particles by using Tiron (4,5-Dihydroxy-1,3-benzene-disulfonic acid, disodium solt monohydrate). Second step synthesis of the addition of hydrolyzed titanium-n-butoxide (TBT) to Au nanoparticles coated with ionized Tiron was applied. TEM observations clarified the presence of Au@TiO2 core-shell particles, whose surface plasmon resonance was thus positioned to longer wavelength due to a high refractive index of TiO2.

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In our previous studies, high-efficient Eu3+ photoluminescence (PL) excited by near-ultraviolet light was reported for Eu3+-doped SnO2-SiO2 glasses, where SnO2 nanocrystals significantly played a role as an energy donor to Eu3+ ion. To obtain blue PL of Ce3+ ions correlated with SnO2 nanocrystal, the methodology of sol-gel fabrication of such glass ceramics in the same route was applied for Ce3+-doped SnO2-SiO2. Stronger PL of Ce3+ blue emission was obtained at the heat-treatment temperature of 800 oC. The color of the PL was whitish blue, due to a broad, long-lifetime PL peaked at 500 nm. Comparing with a blue PL of Ce3+-doped SiO2 glass, it was found that a thermal quenching of Ce3+ blue PL was effectively restricted in the presence of SnO2 nanocrystals. The PL mechanism will be discussed in comparison with that of Eu3+-doped SnO2-SiO2.

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Luminescence properties of Re³⁺(Re=Ce and/or Gd) doped lithium borate glass were investigated by UV, alpha excitation and neutron irradiation. The light yield of the system increased with increasing B₂O₃ content.The decay time was evaluated to be in the range of 30~45ns with compositional dependence.The low density and the high netron absorption with short decay time of this system would be attractive for neutron detection.

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The charge density of the high Tc superconducting material La2-xSrxCuO4 (x=0.12) was investigated by the single-crystal X-ray diffraction and the results were evaluated by theoretical calculations based on molecular orbital and molecular dynamics theories. The difference Fourier maps revealed not only an aspherical electron density distribution around Cu caused by the less populated antibonding molecular orbital between Cu and basal O atoms, but also a local structural relaxation around Sr different from that around La. These results have been obtained only from the best crystal grown by the late professor H. Kojima, Univ. of Yamanashi using the floating-zone method.

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