Katsuyoshi Shimokawa

Fluorescent properties of Tb-doped borosilicate glass films prepared by a sol-gel method

Rare earth elements have been used as optical dopants in glasses for many years. Boro-silicate glass films doped with rare-earths were deposited on glass substrates by using a simple sol-gel method. To avoid the undesirable precipitation due to the different hydrolysis rates between silicon and boron alkoxides, two solutions were used for dip-coating separately. One solution consisted of silicon tetraethoxide, ethanol, water and terbium nitrate as the Tb dopant. Another consisted of triethyl borate. Layer-by-layer deposition was applied by dipping into solutions containing metal alkoxides in sequence. The fluorescence properties of Tb3+ were investigated for the boro-silicate samples in relation to the firing effect. As-deposited silicate and boro-silicate samples showed similar fluorescence spectra under UV excitation. After firings at about 800 degrees C, a remarkable increase of the Tb3+-ion fluorescence was observed for the boro-silicate samples, while the silicate sample showed a little increase in fluorescence intensity. These experimental results suggested the formation of boro- silicate network and the incorporation of Tb3+ into the boro-silicate matrix. The multilayer process was found useful to fabricate multi-component sol-gel films.

Preparation and luminescent properties of sol–gel derived SiO2–B2O3:Tb glass films

Abstract Borosilicate glass films doped with rare-earths were deposited on glass substrates by using a simple sol–gel method. To avoid the undesirable precipitation due to the different hydrolysis rates between silicon and boron alkoxides, two solutions were used for dip-coating separately. One solution consisted of silicon tetraethoxide, ethanol, water and terbium nitrate as the Tb dopant. Another consisted of triethyl borate. Layer-by-layer deposition was applied by dipping into these solutions in sequence. The luminescent properties of Tb 3+ were investigated for the borosilicate samples in relation to the firing effect. After firing at 900 °C, a remarkable increase (≈8 times) of the Tb 3+ -ion luminescence was observed for the borosilicate samples, while the silicate sample showed about 3 times increase in luminescence intensity. The boron addition of as low as 1 mol% of B 2 O 3 was found to be very effective in increasing the Tb 3+ luminescence intensity.

Condition of Exothermic Fusion Reaction into Ti-Ni Alloy and Its Mechanical Properties

A Ni-Ti compact underwent an exothermic fusion reaction during quick heating in a vacuum pressure. Consequently. the phenomena resulted in the purification of the alloy. The application of this technology will simplify the manufacturing process and facilitate quality control of the product. The authors researched the effect of heating rates. vacuum range and gaseous atmosphere on the exothermic fusion reaction in detail. and arrived at the optimum conditions for the reaction. Moreover. porous semi-fused Ti-Ni alloy was produced by the exothermic reaction, under vacuum conditions in a closed silica tube.The Ti-Ni alloys obtained by the exothermic reaction showed mechanical properties comparable with a commercial alloy.