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This paper aims to fabricate over centimeter size of porous silica monolith having meso-pores with large surface area. A precursor of porous silica monolith was obtained by sintering a monolithic SiO2-poly (vinyl alcohol) (PVA) nanocomposite at 600oC-1100oC. The sintering behavior was examined by means of Raman spectroscopy and a porosimetry. The PVA of the SiO2-PVA nanocomposite was combusted below 600oC, subsequently the silica nanoparticles of the nanocomposite were sintered above 900oC. The Raman spectroscopy suggested that amorphous structure of the porous silica monolith obtained above 1000oC was similar to that of a silica glass. The BET surface area and pore radius of the porous silica monolith decreased with increasing sintering temperature. These values were tailored in the range of ca. 0-291 m2.g-1 and 5-25 nm, respectively, by controlling the sintering temperature and time. The fabricated porous-silica monolith was translucent or opaque porous-silica depending on the pore size.

A monolithic silica glass doped with Pr3+ was prepared by immersing a mesoporous SiO2–polyvinly alcohol (PVA) nanocomposite in a Pr nitrate solution and then sintering it at 1100℃ in air. The sintered glass exhibited pink emission when excited by ultraviolet irradiation. The photoluminescence intensity of the glass depended on the total concentration of Pr ions, which was adjusted by changing the concentration of the Pr nitrate solution and the immersion time. The glass with the highest photoluminescence intensity was prepared by using a 1- or 10-mM Pr solution at an immersion time of 60 min. To reveal how the immersion conditions affected the photoluminescence intensity, we analyzed and discussed the adsorption kinetics of the Pr ions onto the surface of the mesoporous nanocomposite. At immersion times below 60 min, the Pr ions diffused into pores of the nanocomposite without aggregating. To prepare Pr3+-doped silica glass with high photoluminescence, both the concentration of the Pr solution and the immersion time must be controlled.

Monolithic silica glasses doped with Cu ions were prepared by immersing a mesoporous SiO 2 -polyvinyl alcohol (PVA) nanocomposite in a copper nitrate solution followed by sintering at 1100 °C for 12 h in air. The Cu ions were reduced from divalent to monovalent during the sintering process and consequently Cu + was doped into the silica glass matrix. The sintered glass possessed blue or yellow photoluminescence (PL) under UV irradiation, depending on the total concentration of Cu ions in the sintered silica glass. At a lower concentration below 30 ppm, the isolated Cu + existed in the glass matrix resulting in the blue PL. However, above 70 ppm, the Cu + –Cu + pairs were present, exhibiting the yellow PL. It was demonstrated that the PL characteristics of the sintered silica glasses doped with monovalent copper ions were affected by the total concentration of Cu ions in the glass, which can be adjusted as a function of the immersion conditions.

Porous monolithic SiO2–poly(vinyl alcohol) (PVA) nanocomposites were fabricated by drying an SiO2–PVA suspension. Depending on the amount of added PVA and pH value of the suspension, the Brunauer–Emmett–Teller surface areas, total pore volumes, and mean pore radii of the (100 − x)SiO2–xPVA (x = 0, 10, 20, 30 wt%) nanocomposites were 102–313 m2 g−1, 0.61–1.42 cm3 g−1, and 8.1–14.7 nm, respectively. Some cracks were observed in the monolithic SiO2–PVA nanocomposite, affected by the pore size. To elucidate crack generation, the correlation between the dispersion/aggregation in the SiO2–PVA suspension and the pore size distribution of the nanocomposite was evaluated in terms of the added PVA amount and pH value. At x = 20 and pH 3, the SiO2 particles and PVA aggregated in the suspension. The preparation of crack-free monolithic SiO2–PVA nanocomposites was possible using the aggregated suspension owing to the low capillary force during drying because of the relatively large pores.

The monolithic silica glass doped with Tb 3+ ions was fabricated using the SiO 2 –PVA nanocomposite as the glass precursor. In order to dope Tb 3+ ions in the monolithic silica glass, the mesoporous SiO 2 –PVA nanocomposite was immersed in the Tb 3+ ions contained solution and subsequently sintered at 1100 °C in air. Consequently the monolithic transparent silica glass was obtained, exhibiting green fluorescence attributed to 5 D 4 → 7 F 5 main transitions under UV excitation. The Tb concentration in the sintered glass could be controlled by immersion time of the nanocomposite in the solution.

Scintillation properties of Ce3+-doped 20Al(PO3)3-80LiF glasses were investigated in order to seek a candidate for down-scattered neutron scintillator in nuclear fusion diagnostics. The decay constant of APLF80 + 3Ce with 5.5 MeV alpha particles from 241Am radioisotope excitation was measured to be 32.1 ns. Moreover, sufficiently low afterglow decay profile and improved light output of APLF80 + 3Ce were experimentally demonstrated.

The surface tension of Bi2O3–B2O3–SiO2 melts was measured using the ring method over the temperature range 973–1573 K. The composition and temperature dependences of the surface tension were investigated. The surface tension of Bi2O3–B2O3–SiO2 melts showed a maximum near 60–70 mol% Bi2O3 and decreased with increasing B2O3/SiO2 ratio at 1373 K. By assuming a linear relationship between the surface tension and the Bi2O3 content of binary silicate melts, the surface tension factor of Bi2O3 was determined to be 211 mN m−1 at 1373 K. The surface tension values calculated using the surface tension factor of each single component showed the largest deviation from the measured values when the Bi2O3 content was around 50–60% and were dependent on the B2O3 content. The temperature coefficient of surface tension had positive values at low Bi2O3 contents (less than 30–40 mol%) and negative values at high Bi2O3 contents.

A nanocomposite was prepared from fumed silica and PVA. Investigation of the morphology of the composite by TEM and electron energy-loss spectroscopy reveals that the nanocomposite consists of homogeneously dispersed SiO2 nanoparticles and PVA. Micropatterns on the nanocomposite were fabricated by room-temperature imprinting. Micropatterned silica glass was obtained by sintering the nanocomposite at 1100°C in air.

We propose a novel noncontact method for measuring the viscosity of high-temperature glass melt using a small amount of sample. This method combines the electric-field tweezers system developed for measuring the local and dynamic surface properties of soft condensed materials and the hot-thermocouple technique for in situ observation and measurement of high-temperature liquids. The viscosity of B2O3 melt was measured in the temperature range of 873 to 1473 K. The temperature dependence of the viscosity presented in this work is in reasonable agreement with that reported in the references.

We present a procedure for fabricating transparent silica glass that involves the sintering of green bodies prepared from an inorganic–organic nanocomposite. The nanocomposite was prepared from fumed silica and poly(vinyl alcohol) (PVA). We investigated the SiO2–PVA nanocomposite by Fourier transform infrared spectrometry (FT-IR) measurement, transmission electron microscopy and electron energy-loss spectroscopy, and the results revealed homogeneously dispersed SiO2 nanoparticles and PVA. We examined the relationship between the pH and ζ potential of the SiO2 suspension and the formability of the SiO2–PVA nanocomposite. Formability of the SiO2–PVA nanocomposite was dependent on the pH of the SiO2 suspension, and a monolithic SiO2–PVA nanocomposite without cracks was obtained using a SiO2 suspension at around the isoelectric point (pI). By sintering the SiO2–PVA nanocomposite in air at 1100°C, monolithic transparent silica glass was obtained with no cracks. The glass is highly transparent from the ultraviolet to the visible region.

A novel custom-developed scintillator for laser fusion diagnostics is reported. With the aim of diagnosing scattered neutrons from the imploded high-density fusion plasma, a fast response lithium-6 glass scintillator has been developed. Praseodymium, instead of the more widely-used cerium was chosen as the dopant. Sufficiently fast luminescence lifetime for scattered neutron diagnostics (

Scintillation properties of Pr3+-doped 20Al(PO3)3-80 LiF glasses melted in N2 were investigated to seek a candidate for a scattered neutron scintillator in nuclear fusion diagnostics. The fluorescence lifetime of the sample with 217 nm ultraviolet femtosecond pulse excitation was measured to be 19.5 ns. More importantly, the fluorescence lifetime with alpha particles from 241Am radioisotope excitation was determined to be 6.7 ns. Based on our material design strategy, we have successfully developed the fast response time praseodymium-doped 6Li glass scintillator for scattered neutron diagnostics.

The effect of mixing ratio, firing temperature and matrix glass composition on afterglow luminance property of SrAl 2 O 4 : Eu 2+ ,Dy 3+ -glass composites were investigated. As a result, the brightness showed a maximum at 35 mass % of the mixing ratio of the phosphor for the glass and 780°C of the firing temperature. And it was increased with decreasing the Na 2 O content of the matrix glass. From the backscattered electron and the EDX analysis, it is thought that the intermediate layers generated between the phosphors and the Na 2 O-poor matrix glass work as antireflective and the phosphor particles in the composite emit phosphorescent light more efficiently. As higher the basicity parameter, B, the intermediate layer was clearer, which means that the reactivity at the phosphor/glass boundaries was lower, and the narrow reaction layers was formed.

The density of oxide glass including silicate, borate, phosphate, tellurite, and germanate glasses were measured using the Archimedes method. On the assumption that the ionic packing ratio is approximately a constant independent of chemical composition, an empirical equation for estimating the density from chemical composition was proposed. The calculated values are in reasonable agreement with the corresponding measured ones.

Antimicrobial activities of porcelain glazes with antimicrobial agents made of clay minerals intercalated with silver chelate and the effect of additives to the antimicrobial agents on those activities were investigated. The glazes with 10 mass % antimicrobial agents, fired at 1573 K in a reducing atmosphere, showed negative antimicrobial activities. On the other hand, the antimicrobial activities of the glazes with 1–10 mass % of the agents fired in an oxidizing atmosphere were positive. The glaze with an agent doped with Zr had a high antimicrobial activity by adding only 0.2 mass % of the agent, which included only 0.008 mass % Ag in the glaze. Wavelength-dispersive X-ray fluorescence, used for ingredient analysis, showed that the negative activity resulted from the disappearance of the Ag in the glaze fired in the reducing atmosphere.

BaO–TeO2 thin films were prepared from tellurium(VI) alkoxide by a sol–gel method and their structure was investigated by X-ray diffractometry, Fourier transform infrared spectrometry, and 125Te static nuclear magnetic resonance. Their crystallization temperature (Tc), optical transmittance, and dielectric constant were measured, and their refractive index was calculated from the transmission spectra. The results indicate that the BaO–TeO2 thin films were composed of TeO6 and TeO4 units, and had a Tc of ∼520°C, refractive index of ∼1.79, dielectric constant of ∼20. These films had a Tc higher than the glass prepared by a melt-quench method, but their refractive index and dielectric constant were lower. These differences may be due to differences in their structural units.

Scatterers observed in lithium tetraborate (Li2B4O7) crystals grown by the Czochralski (CZ) method, were examined. It was revealed that the scattering source may decrease transparency in the ultraviolet (UV) region, which is an important property for application in nonlinear devices in the UV region. Parameters necessary for the reproducible growth of scatterer-free Li2B4O7 crystals were also investigated and scatterer-free Li2B4O7 crystals were successfully grown in dry air flow. Particles forming the scattering source were evaluated and the H concentration of the crystals was also examined.

We applied the scaffold-free culture method to chondrocytes and attempted to reconstitute articular cartilage grafts. Primary rat costal chondrocytes were immobilized into hollow fibers by centrifugation at a density of 3 x 10(8) cells/cm(3) to induce the formation of cylindrical-shaped multicellular aggregates (organoids) and cultured for one month. The organoids were evaluated by histological and gene expression analyses. Chondrocytes formed cylindrical organoids in hollow fibers (HFs). Histochemical analysis revealed the accumulation of a cartilage extracellular matrix (collagen and proteoglycan) around cells in the lumen of HFs with culture time, forming a low-cellular-density tissue similar to native cartilage by day 28. Furthermore, in contrast to that in traditional monolayer culture, the organoid maintained the gene expression of the cartilage extracellular matrix (type II collagen, aggrecan) for one month of culture. In conclusion, our organoid formation method was effective in producing a cartilage-like tissue. This result suggests that the technique may be applicable to the development of an articular cartilage graft.

Transparent silica glasses were obtained by sintering a green compact in diverse atmospheres. The green compacts were fabricated by slip-casting methods for high-purity silica glass powder. The relationships between sintering atmosphere and sintering temperature that result in transparent, sintered silica glass were shown. It was found that the transparency-forming region of sintered silica glass corresponds to a sintering temperature above 1400°C and high-vacuum (10−4 Pa) atmosphere conditions. We investigate the fabrication of transparent and hydroxyl-free silica glass by a powder-sintered method. The sintered silica glass with 10 ppm OH content exhibited the highest transmittance at 157 nm (76% for 2 mm sample thickness). Refractive index dispersion curves in the wavelength region of 0.194μm to 3.584μm are presented for the sintered silica glass by minimum deviation method.

This paper aims to fabricate microhole arrays onto a silica glass via a room temperature imprint and subsequent sintering by using a monolithic SiO2-poly(vinyl alcohol) (PVA) nanocomposite as the silica glass precursor. The SiO2-PVA suspension was prepared from fumed silica particles and PVA, followed by drying to obtain tailored SiO2-PVA nanocomposites. The dependence of particle size of the fumed silica particles on pore size of the nanocomposite was examined. Nanocomposites prepared from 7 nm silica particles possessed suitable mesopores, whereas the corresponding nanocomposites prepared from 30 nm silica particles hardly possessed mesopores. The pore size of the nanocomposites increased as a function of decreasing pH of the SiO2-PVA suspension. As a consequence, the crack-free monolithic SiO2-PVA nanocomposite was obtained using 7 nm silica particles via the suspension at pH 3. Micropatterns were imprinted on the monolithic SiO2-PVA nanocomposite at room temperature. The imprinted nanocomposite was sintered to a transparent silica glass at 1200°C in air. The fabricated sintered glass possessed the microhole array on their surface with aspect ratios identical to the mold.

Dielectric constants were measured for phosphate and silica glass systems in the frequency region of 1 to 10 GHz using the resonance cavity method. Compositional dependence of dielectric constant and tangent loss were discussed. The effect of the cations on the ε indicates that ε increases in the order, R:Mg

A graded glass coating for Vitallium®, a Co-Cr alloy, has been prepared using a simple enameling technique. The composition of the glasses has been tailored to match the thermal expansion of the alloys. The optimum glass composition and firing conditions (temperature and time) needed to fabricate homogeneous coatings with good adhesion to the alloy were determined. The final coating thickness ranged between 25 and 60 μm. Coatings fired under optimum conditions do not delaminate during indentation tests of adhesion. Excellent adhesion to the alloy has been achieved through the formation of 100 nm thick interfacial chromium-oxide (CrOx) layers. The graded glass (consisting of BIG and 6P50 layers) can be successfully coated to a Co-Cr alloy, and forms hydroxyapatite (HA) on the coating surface when immersed in a simulated body fluid (SBF) for 30 days.

The surface tensions of xPbO-(100−x) B2O3 (x = 30–80 mol%) and xBi2O3-(100−x) B2O3 (x = 0–100 mol%) melts were measured using the ring method over the temperature range 973 to 1373 K. The compositional and temperature dependences of surface tension were investigated. Addition of PbO and Bi2O3 to B2O3 increased the surface tensions of their respective PbO-B2O3 and Bi2O3-B2O3 melts. The surface tension showed a maximum at 60 mol% PbO in the PbO-B2O3 melts and at 70–80 mol% Bi2O3 in the Bi2O3-B2O3 melts. The temperature coefficient of surface tension was examined on the basis of its relationship to the structure, and it was suggested that the temperature coefficient of surface tension decreases with an increasing content of four-coordinated boron.

Hydroxyapatite dispersed glass coatings on Vitallium®, a cobalt-chromium alloy were prepared using a simple enameling technique. The composition of the bioinert glasses in the SiO2-B2O3-Na2O-K2O-MgO-Al2O3-ZrO2-TiO2 system has been tailored to match the thermal expansion of the alloys. The optimum glass composition and firing conditions (temperature and time) needed to fabricate homogeneous coatings with good adhesion to the alloy were determined. The final coating thickness ranged between 40 to 60 μm. Coatings fired under the optimum conditions do not delaminate during indentation tests of adhesion. Excellent adhesion to the alloy has been achieved through the formation of 200 nm thick interfacial layers (CrOx). X-ray diffraction patterns for the hydroxyapatite dispersed on the glass surface showed a strong preferred orientation of the (0 0 2) plane when immersed in a simulated body fluid (SBF).

We report the vacuum ultraviolet (VUV) spectroscopy of APLF + Nd and APLF + Er glass, with composition 20Al(PO3)3-80LiF + 1NdF3 and + 1ErF3 (in mol%). APLF + Nd and APLF + Er have a dominant fluorescence peak at 185 nm and 168 nm with decay times of 4.5 ns and 5.8 ns, respectively. Fluorescence from APLF + Nd is attributed to 4f25d → 4f3 transitions in neodymium (Nd) while fluorescence from APLF + Er is due to spin allowed transition in erbium (Er). This is the first report of VUV fluorescence from rare earth ions doped in glass hosts, which could provide the basis for mass production of VUV emitting materials. Our results also suggest the potential of using APLF + Nd and APLF + Er as neutron scintillators during inertial confinement fusion.

We explore the potential of Pr- or Ce-doped 20Al(PO3)3–80LiF (APLF80+3Pr or +3Ce) scintillator to observe the lower edge of down-scattered neutron and discriminate fusion originated neutron from strong X-ray signals. APLF80+3Pr or +3Ce scintillator exhibits considerably fast decay profiles and negligible slow-decay components. Using these newly developed APLF80+3Pr or +3Ce scintillators, we have successfully observed fusion-originated neutron signal in the midst of strong X-ray-excited fluorescence in an integrated experiment using our 10 kJ class GEKKO XII Nd-glass laser system. A sophisticated neutron detection system using APLF80+3Pr or 3Ce will be used for the first fast ignition experiment.

The Young's moduli of various oxide glasses (silicate, borate, phosphate, and tellurite) were measured using an ultrasonic method. To predict the Young's moduli of the oxide glass systems, empirical compositional parameters Gi and Vi, based on the Makishima-Mackenzie theory, were obtained, where Gi is the dissociation energy and Vi the packing density parameter of a single-component oxide. The relationship between the calculated Young's modulus from the compositional parameters and the measured Young's modulus was investigated. Experimental results indicated that the Young's modulus of phosphate and tellurite glasses could not be predicted using these parameters. Thus, it was necessary to modify the Gi, by considering P2O5 and TeO2 as glass network formers. As for the phosphate glass, it exhibited a layered structure that consisted of P=O double bond and three chains of P-O bond. In this paper, the modified Gi of P2O5 was calculated using the assumption that the P=O double bond is a nonbridging bond and does not contribute to Young's modulus. In the case of tellurite glass, the glass structure is mainly composed of TeO4 trigonal pyramids, and the addition of other oxides results in structural changes to the TeO3 trigonal pyramid. However, the mechanisms of such structural changes have not yet been clarified. Therefore, the modified Gi of TeO2 was calculated from the measured value using the density and Young's modulus of pure TeO2 glass. The results revealed that the calculated values using our proposed parameter were in good agreement with measured values all through the oxide glasses.

The densities of xBi2O3·(100−x)B2O3 binary melts (x= 0–100 mol%) have been measured systematically in the temperature range of 973 to 1373 K using the Archimedean double-bob method. In addition, the molar volume and coefficient of volume expansion have been determined from these density measurements. The density of melts in the Bi2O3–B2O3 binary system decreased with increasing temperature for all compositions, and increased with increasing Bi2O3 content. The molar volume calculated at 1273 K showed a minimum at around 20–30 mol% Bi2O3. The deviation of molar volume from ideality and the partial molar volumes of B2O3 and Bi2O3 single-component melts were calculated, and the relationships between these properties and Bi2O3 content were investigated. The Δ(MV) (deviation of molar volume from ideality) was negative in the Bi2O3–B2O3 binary melts and showed a minimum of −7.5 cm3 (−17.3%) at 40 mol% Bi2O3 and 1273 K. The PMV (partial molar volume) of the B2O3 melt decreased with increasing Bi2O3 content, up to 70 mol% Bi2O3, and was constant above 70 mol% Bi2O3. The PMV of the Bi2O3 melt was constant up to 30 mol% B2O3 (considered from the viewpoint of Bi2O3), and then decreased sharply with further addition of B2O3. The coefficient of volume expansion increased sharply up to 20 mol% Bi2O3 and decreased with further addition of Bi2O3 at 1273 K. From this result, it can be inferred that the temperature-induced structural changes taking place in the melts are greatest at 20 mol% Bi2O3.

Two series of three-dimensional (3-D) numerical simulations were conducted in order to understand 3-D Marangoni convection in half-zone liquid bridges of molten tin. In one series, we determined the second critical Marangoni number for liquid bridges of low-Prandtl-number fluid ( Pr =0.009) at different aspect ratios, As, based on the well-known simple bridge geometry which assumes the liquid bridge is supported between two differentially heated isothermal solid discs. A new type of oscillatory flow was first observed in a simulation of a tin liquid bridge of As=2.0 under highly supercritical conditions at Ma=1.4 Ma c 2 , the whole flow and temperature fields with an azimuthal wave number m =1, exhibiting an apparently twisting oscillations back and forth around the axis, rotates very slowly in the azimuthal direction. In the second series, we conducted numerical simulations based on much realistic bridge geometry. Special emphasis was placed on the effects of less conductive supporting rods on the stability limit of the axisymmetric steady flow and the onset of flow oscillations. Present simulations reveal that the 3-D flow causes non-uniform temperature distributions in the supporting rods. We proposed a new definition of effective temperature difference (Δ T e ) acting on the liquid surface to evaluate the Marangoni number. Thus determined first and second critical Marangoni numbers fall close to, but slightly larger than, those predicted by the simple model. However the deviations are less than 3%. On the other hand, present simulations revealed that very small spatial offsets of temperature measuring points cause significant error in Δ T measurement because of the conduction resistance in the rod under large heat flux. This effect is very important for any liquid bridge experiments using low- Pr fluid. A simple conduction dominant model provides reasonable estimate of Δ T e from the temperature difference measured by thermocouples.

The density, surface tension, and viscosity of the melts from the PbO-B2O3-SiO2 system have been measured at temperatures in the range 1073–1473 K. The effect of composition on these properties was also investigated. The density of the melt was found to increase linearly with increasing PbO content. Molar volume was derived from the density data, and its deviation from the additivity of partial molar volumes was calculated. These deviations in molar volume from those obtained from additivity rules have been used along with the ratio of various coordination numbers of boron (as reported by Bray) to discuss the structure of the melts. The surface tension was found to decrease with decreasing SiO2/B2O3 ratio, and to increase in the range of the PbO content between 30 and 60 mol%, showing a maximum at ∼60 mol% PbO, and then decreased with further additions. This result suggested that the surface tension would be affected primarily by the B2O3 content in the range of the PbO content between 30–60 mol%, and mainly by the PbO content in the range of the PbO content >60 mol%, respectively. The viscosity of the melt was found to decrease linearly with increasing PbO content. The results obtained indicate that the increase in viscosity with B2O3 was half that of SiO2 (on a molar basis), and an empirical equation has been proposed for the viscosity as a function of mole fraction.

Transparent pyrex glasses were obtained by sintering a green compact, which was fabricated by using CIP method for pyrex glass powder, in diverse atmosphere (air, Ar, He and vacuum (10-2Pa)) at 973-1173K. Effects of sintering conditions (temperature and atmosphere) on transmittance of sintered glasses were investigated. Devitrification resulting from crystallization of cristobalite arose in all atmosphere at temperatures over 1023K. Optimum sintering condition for fabricating transparent sintered pyrex glass was at 1003 K for 1hour in a vacuum (10-2 Pa) or He atmosphere in this work. The transparency was 15∼20% in visible region and was about 60% in infrared region. The relationship between transparency and condition of the sintered glasses was discussed in terms of permeation constant of gas species during sintering.

Silicate glass coatings on Vitallium®, a Co-Cr alloy were prepared using a simple enameling technique. The composition of the glasses in the SiO 2 -Na 2 O-K 2 O-MgO-Ca0-P205 system has been tailored to match the thermal expansion of the alloys. The optimum glass composition and firing conditions (temperature and time) needed to fabricate homogeneous coatings with good adhesion to the alloy were determined. The final coating thickness ranged between 40 and 60 μm. Coatings fired under the optimum conditions do not delaminate during indentation tests of adhesion. Excellent adhesion to the alloy has been achieved through the formation of 150 nm thick interfacial layers (CrOx). The silicate glass can be successfully coated to Co-Cr alloy and formed hydroxyapatite on the glass surface when immersed in a simulated body fluid (SBF) for 30 days.

The density, surface tension and viscosity of the 50RO–50P2O5 (R: Mg, Ca, Sr, Ba and Zn) glass melts have been measured over the range, 1073–1623 K. The effects of R cations on these properties have been investigated. The density of the melt was found to increase in the order, R: Mg Ca Zn Sr Ba, with increasing molar weight of cation. The surface tension in the temperature range of 1373–1473 K increased approximately with cation in the order, R: Zn Ba Mg Ca Sr. The viscosity and the negative, temperature coefficient of surface tension increased in the order, R: Ba Sr Ca Zn Mg. All melts exhibited negative temperature coefficients of surface tension. The effect of Mg and Zn cations on the properties were different to that for Ba, Sr, and Ca cations and this is discussed using bulk glass data published in a previous report. The features of Mg and Zn metaphosphate glass melts, that is high values of viscosity, and temperature coefficient of surface tension, are related to the small Oxygen Coordination Number of the cations (=4) when compared with those of Ca, Sr, Ba metaphosphate glass melts.

Transparent silica glasses were obtained by sintering a green compact (fabricated by slip-casting methods for high-purity silica glass powder) in diverse atmospheres. The relationships between sintering atmosphere and sintering temperature that result in transparent, sintered silica glass were shown. The results indicate that there are four forming phases for each sintering atmosphere and temperature: (1) nontransparent glass resulting from an overabundance of pores (2) crystal, such as cristobalite or β-quartz, (3) moganite, and (4) transparent glass. Optimum sintering temperature for fabricating transparent silica glass was above 1673 K in a high-vacuum (10−4 Pa: p(O2)=10−14) atmosphere. We investigate the fabrication of transparent and hydroxyl-free silica glass by a powder-sintered method. After studying the effect of sintering schedule on residual [OH−] concentration for transparent, sintered silica glasses, we sintered a green compact prepared by silica powders with a mean particle size of 1.6 μm, first heating it to 1523 K for dehydration and then to 1873 K for densification. This typical fabricated condition resulted in a transparent, sintered silica glass with

Optical transmission and refractive indexes in vacuum ultraviolet (VUV) region are very important and provide basic data for lens systems in micro lithography equipments and substrate materials using F2 excimer laser as a lightsource. High purity multi-component fluoroberyllate glasses are promising candidates for the deep UV transmitting optical materials due to their exceptionally large optical band gaps compared to those of the other fluoride glass systems. The optimum glass composition for VUV glass material were introduced in terms of glass forming ability and VUV absorption of impurities in the glasses. We also measured refractive indexes of the glasses in VUV region. In order to predict the refractive index, we presented compositional parameter for fluoride glass based on our measured data.

In this paper, the phase transformations that occur during the thermal decomposition of ammonium aluminum carbonate hydroxide (AACH) into α-Al 2 O 3 have been studied. Amorphous, γ-, and θ-Al 2 O 3 were identified as intermediate products. A time-temperature-transformation (TTT) diagram for thermal decomposition in air was determined. The critical particle size of θ-Al 2 O 3 in the θ→α phase transformation is ∼30 nm; the size does not depend on the firing atmosphere. However, the atmosphere affects the grain size distribution of the final α-Al 2 O 3 particles. Powders with an average grain size of 60 nm were obtained by firing in vacuum or hydrogen.

The density, surface tension and viscosity of the molten PbO-B2O3-SiO2 system were measured for high packaging industry. The compositional dependence of the properties has been investigated. The results were shown as follows. The density of melt increase linearly with increasing PbO content. The molar volume was estimated from the density data and its deviation from additivity was calculated. It was considered that Pb2+ ions may act as a network former for PbO content more than 40-50mol%. The surface tension decreased with decreasing the ratio SiO2/B2O3, and its value increased at 30 60mol%, respectively. The viscosity of melt decreased linearly with increasing the PbO content. To predict the viscosity, an empirical equation between viscosity and molar equivalent weight was obtained, from which the effect of viscosity; B2O3=SiO2×0.5 was presumed.

Refractive indexes of oxide glasses: silica, borate, silicate, aluminate, germanate, tellurite, antimonate and heavy metal gallate are measured in the wavelength range of 0.40–5.03 μm. The zero material dispersion wavelength (ZMDW) was determined using the refractive index data. To predict the ZMDW, we calculated the molecular electronic polarizability, α i , of oxide glasses using the Lorentz-Lorenz equation. An empirical equation between ZMDW and α i was obtained, from which the ZMDW from the compositional parameter, α i can be calculated.

Refractive index dispersion curves in the wavelength region of 0.40 to 5.03 μm are presented for multi-component oxide glass systems: borate, silicate, aluminate, germanate, tellurite, antimonate and heavy metal gallate. The material dispersion was determined using the refractive index data. Reflection spectra in the ultraviolet and infrared regions were measured to investigate the effects of electronic transitions and lattice vibrations on the material dispersion. Thallium tellurite, thallium antimonate and lead gallate glasses exhibit zero material dispersion wavelengths (ZMDWs) over 2.4 μm. The factors affecting the ZMDW are discussed.

BaO-B2O3-SiO2, PbO-SiO2 and PbO-B2O3 glasses were polished using a pitch polisher and cerium oxide dispersed in distilled water. The factors affecting the polishing rate at initial stage were discussed in terms of glass properties: Vickers microhardness, chemical water durability and bulk modulus. The polishing rate of BaO-B2O3-SiO2 glasses depends mainly on the hardness of the hydrated layer formed; this factor is consistent with Izumitani proposal. The polishing rates of PbO-SiO2 and PbO-B2O3 glasses increase with increasing PbO content up to 50mol% PbO and then decrease remarkably. The polishing rates of PbO-SiO2 and PbO-B2O3 glasses are apparently affected by the bulk modules which is related to the product of the ratio of plastic strain to elastic strain (c/a) and the indentation hardness H using Hill's theory on plastic-elastic materials.