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Transparent low-melting inorganic glass is an attractive industrial material based on its high thermal and light resistance compared with conventional engineering plastics. If the melting temperature of inorganic glass could be decreased, the doping of guest materials or compression moulding on the glass surface would be easier. Although phosphate glass is considered as a potential candidate because of its transparency in the visible region and low-melting behaviour, water durability often becomes a problem for implementation. Here, we prepared inorganic low-melting phosphate glass at a temperature of 500 °C via a melting and quenching methodology. It was found that tin-doped phosphate glasses exhibited higher thermal and light resistance properties than polycarbonates. Colourless transparent oxide glasses without organic components are capable of bringing about new possibilities for the application of inorganic glasses.

A viscoelastic study of the 25GeS2-55SbS3/2-20SnS and 12.5GaS3/2-75SbS3/2–12.5SnS sulfide glasses was carried out around their deformation temperatures using a uniaxial compression creep test. Their viscosities showed similar temperature dependences, but slightly lower sensitivity was observed for the latter glass than for the former glass, which may be explained by the theory of free volume. The creep function, derived from the displacement of the height of the sample subjected to a creep test, was converted into relaxation moduli by performing a Laplace transformation and its inversion. The shear relaxation moduli G(t) revealed two distinct structural relaxation processes, specifically with short and long relaxation times. Both the major fast-relaxation process and minor slow-relaxation process obeyed the time–temperature superposition principle. The fast-relaxation activation energies for both glasses were estimated to be about 390 kJ/mol. This value was close to the dissociation energy of the Sb—S bond, which formed the major cross-links of the glass network. In contrast, slow-relaxation activation energies of approximately 590 and 550 kJ/mol were determined for the GeS2-containing and GaS3/2-containing glasses, respectively. The slow-relaxation process, having a higher activation energy for the GeS2-containing glass than for the GaS3/2-containing glass, was concluded to have involved dissociation and recombination, even at high temperatures, of the stronger crosslinks made of the Ge—S and Ga—S bonds in the glass network.

The viscoelastic behavior of alkali and alkaline earth aluminophosphate glasses was studied. The energetic interpretation was based on the Arrhenius behavior of the relaxation modulus. With increasing aluminum content, the activation energy of the relaxation increased in the alkali series but decreased in the alkaline earth series. Dynamic viscoelasticity measurements revealed that the loss modulus, E”(ω), showed a crossover of the relaxation process at the glass transition temperatures. The activation energy below the transition temperature was close to the energies of internal friction or ionic self-diffusion. The energy above the transition temperature corresponded to the dissociation energies of alkali-oxygen or alkaline earth-oxygen single bonds. The different behavior in the energy of the relaxation modulus between alkali and alkaline earth series was due to weak bonds caused by adding alkali ions and the formation of crosslinking by low-coordinate aluminum polyhedra because of the presence of alkaline earth ions.

Transparent low-melting inorganic glass is an attractive industrial material based on its high thermal and light resistance compared with conventional engineering plastics. If the melting temperature of inorganic glass could be decreased, the doping of guest materials or compression moulding on the glass surface would be easier. Although phosphate glass is considered as a potential candidate because of its transparency in the visible region and low-melting behaviour, water durability often becomes a problem for implementation. Here, we prepared inorganic low-melting phosphate glass at a temperature of 500 °C via a melting and quenching methodology. It was found that tin-doped phosphate glasses exhibited higher thermal and light resistance properties than polycarbonates. Colourless transparent oxide glasses without organic components are capable of bringing about new possibilities for the application of inorganic glasses.

Chalcogenide glasses have attracted a great deal of attention for the optical elements of infrared devices. The viscosity and elasticity of glasses are important characteristics for the use of precision molding techniques. The uniaxial compression creep behavior of Ge20Sb15Se65 glass was studied around its deformation temperature. The derived creep function was converted into relaxation moduli by Laplace transformation and its inversion. Analysis using a two-term Maxwell model revealed the shear relaxation modulus G(t) as two distinct structural relaxation processes with short and long relaxation times on the order of 101 s and 103 s, respectively, at 313 °C. The fast relaxation with high elasticity obeyed the time–temperature superposition principle and its activation energy ΔH1 was estimated to be 350 ± 10 kJ/mol using Narayanaswamy's relation. This energy is mainly comparable to the bond dissociation energies of Se Se (~320 kJ/mol). The process was therefore suggested to be due to motion around these thermally broken inter-atomic bonds, as in many glassy systems. In contrast, the low-elasticity slow relaxation process had activation energy of approximately 480 ± 60 kJ/mol and was considered to represent breaking and rearrangement of heteronuclear Ge Se and Sb Se bonds in the glass network during pressure-induced entanglement.

In addition to the total attenuation of ionizing radiation, photoluminescence has been conventionally recognized to affect radiation-induced luminescence. In this study, we examined the optical and luminescence properties of Ce3+ in lithium silicate-based glasses with different optical basicities. The existence of Ce4+ was confirmed based on the optical absorption, Ce L3-edge X-ray absorption near edge structure (XANES), and optical coefficients of the calculated Ce4+ using the optical absorption and XANES data of Ce4+ species from a previous report. Compared to other multicomponent glasses, there was a slight deviation in the decay constant and quantum yield (QY) of the stoichiometric Li2O–2SiO2 glass. In addition, the light yields calculated from the pulse height spectra with 252Cf irradiation depend on the QY of the glasses. Considering the energy conversion process, the dependence of the light yield agreed with that of the conventional energy conversion process of neutron-induced luminescence.

The macroscopic elastic modulus of a solid-state matter is generally affected by the packing density and average bond strength of the constituent atoms. However, because of the diversity of network connections in oxide glasses, an understanding based on the network structure is also required for precise structural categorisation. Here, we examine the relationship between the elastic modulus and structural parameters, viz., the correlation length of the Boson peak and cavity size calculated from the positron annihilation measurement, of BaO-TiO2-GeO2-SiO2 glasses. The Poisson's ratio correlates with the ratio of the longitudinal and transversal sound velocities, and thermal stability parameter ΔT. The Boson peak frequencies of these glasses at the GeO2-rich region exhibit an apparent plateau behavior, indicating that the rate of change in the sound velocity is similar to that in the correlation length. Although the numerical calculation of the cavity in this glass by positron annihilation spectroscopy is unavailable because of the d -electron of Ti cations, the τ1 value shows a similar compositional dependence as the correlation length of the Boson peak. It is expected that a combination of elastic modulus and inelastic light scattering of glasses will be helpful in understanding glass-forming melts.

We have examined the X-ray-induced luminescence of Sn-doped zinc borate (SZB) glasses prepared by a conventional melt-quenching method in an Ar atmosphere, determining that there is a linear relationship between the thermal properties and SnO, in addition to the elastic properties. The scintillation intensity of SZB glasses increases with tin concentration. Meanwhile, the intensity of thermally stimulated luminescence (TSL) achieves a maximum peak area in the sample with 0.1 mol% Sn concentration. A clear inverse relationship between scintillation and TSL in SZB glasses is observed.

A procedure for determining the crystal system of a microcrystalline powder is described. In this procedure, in situ X-ray diffraction measurements are performed on a microcrystal suspension oriented uniaxially under static and rotating magnetic fields. This is followed by the classification of the obtained diffraction images using a flowchart proposed in this study. To demonstrate the validity of this procedure, diffraction images were recorded for microcrystalline suspensions prepared from known crystal systems including triclinic (d-arabitol), monoclinic (cellobiose), orthorhombic (l-alanine), tetragonal (urea), trigonal (bismuth, calcite), hexagonal (zinc), and cubic (sodium chloride) systems. The crystals were classified into their respective crystal systems following the proposed procedure. The determined crystal systems for biaxial crystals were consistent with the reported crystal systems of the microcrystalline powders investigated. Herein, determination of the lattice parameters and space groups...

ZnF2 thin films were deposited on SiO2-glass and Al2O3-single crystal substrates using electron-beam evaporation, and the morphology of the films was studied in relation to the kind of substrate and deposition conditions. While the films deposited on SiO2-glass, (11 2 ¯ 0)-Al2O3 substrates exhibited an almost non-oriented polycrystalline nature, the films deposited on (0001)-Al2O3 substrates were epitaxially grown (100)-oriented films. The full-width at half maximum of the rocking curve of (200)-diffraction for the (100)-oriented film deposited at 400 °C was 150″. This value was comparatively small compared with previously reported (100)-oriented SnO2 and TiO2 films and showed the high orientation and crystallinity of the ZnF2 film. From the transmission spectra from near-infrared (NIR) to vacuum ultraviolet (VUV), the optical band gap of the ZnF2 was evaluated to be 6.7 eV, and the films exhibited high transparency in the wide range from NIR to VUV. We discuss the potential of the film as a transparent conducting material in the VUV region.

Carbon/silica composite films were prepared from colloidal silica aqueous solution in which vapour grown carbon nano-fibers were dispersed. The orientation of nano-fibers was attempted by dip-coating substrates under high magnetic field up to 10 T. The fibers started to align along the direction of magnetic field below 1 T. The degree of orientation was saturated at about 6 T. The anisotropic susceptibility, Δχ = χ// − χb, was estimated to be (3.05 ± 1.10) × 10−7 cm3/mol from the fitting of numerical simulation. Optical anisotropy, the ratio between transmittances of light polarized perpendicular to and parallel to the direction of fiber orientation, increased immediately in the films prepared under applied fields below 1 T and almost saturated above 1 T. The optical anisotropy was in good agreement with the behaviour of magnetic orientation of fibers.

We have developed zinc-bismuth-phosphate glasses, which have deformation temperatures under 450°C and refractive indices higher than 1.7, in order to produce an antireflection structure on the surface by a glass-imprinting process. Two-dimensionally arrayed conical cavities of sub-wavelength size were fabricated on a SiC mold by electron lithography and dry etching techniques. The sub-wavelength periodic structure was transferred onto the glass surface by a glass-imprinting process using the mold. The sub-wavelength structure suppressed the reflectance by approximately 90%. A weak maximum was observed in the reflection spectra around 400–500 nm, which decreased in intensity and shifted toward shorter wavelengths with decreasing pitch.

Optical properties were studied on ternary zinc bismuth phosphate glasses, which have two distinct glass-forming regions; low-P2O5 region and high-P2O5 region. Orthophosphate and isolated phosphate structures are dominant in the former region and metaphosphate and pyrophosphate structures are dominant in the latter region. Refractive index of the low-P2O5 glass (nd > 1.82) was relatively higher than that of the high-P2O5 glass (nd O bonding state between two glasses.

Hydrogenation / dehydrogenation properties of a series of ternary face centered cubic (FCC) hydrides “Mg7MHx” (M = Sc, Ti, V, Zr, Nb, Hf and Ta), which were prepared by a high-pressure technique, were investigated. Differential scanning calorimeter (DSC) measurements under hydrogen atmosphere revealed that these hydrides exhibited reversible hydrogen releasing and re-storing properties at around 600 and 560 K, respectively. These releasing temperatures are lower by 100 ~ 120 K than that of MgH2. Furthermore, pressure-composition isotherm at 523 K shows that these FCC hydrides release 3.8 - 5 wt. % hydrogens.

Surface modification was performed on high-pressure densified silica glass by CO laser irradiation. Microbumps were formed on the silica glass surface due to the relaxation of the compacted structure by the irradiation. The relaxed area reached a depth of about 40 µm, and the volume expansion estimated from the relaxed area was consistent with the volume expansion at the surface. The microbumps were arrayed at a minimum interval of 15 µm, which acted as a microlens array. Moreover, microbumps were formed successfully on both sides of the thin glass plate by irradiation from one side.

The optical property of Li2O-Al2O3-SiO2 glass-ceramic, with a near-zero thermal expansion coefficient, crystallized under high pressure has been studied. A hydrostatic pressure of 196 MPa was applied by a hot isostatic pressing (HIP) technique during the nucleation process and the crystal growth process. The temperature coefficient of the optical path length, 1/l•dS/dT, decreased by 0.6×10-6 K-1, because the temperature coefficient of the refractive index, dn/dT, was decreased by the HIP treatment. The decrease in dn/dT was ascribed to the suppression of the temperature coefficient of the molar polarizability, φ, of the glass-ceramic crystallized by the HIP treatment. It was concluded that the suppression of φ occurs in the crystalline phase during the HIP treatment, based on the fact that the reduced 1/l•dS/dT was maintained even after the relaxation of the densified structure in the glass phase upon thermal annealing. The decrease in the number of lattice defects in the crystalline phase was hypothesized to be a cause of the reduced φ.

We synthesized polyfluorene-based polymers as a blue emitting material of polymeric light-emitting diodes (PLEDs). PLEDs using high-molecular-weight component are found to have high luminance and efficiency for high fluorescence quantum yield of materials. We prepared devices using poly(9,9-dioctylfluorene) (PDOF) with different molecular-weight distributions. Electroluminescence characteristics of devices using the PDOF with the high-molecular-weight component were superior to those of the devices using PDOF with the low-molecular-weight component.

Halogen ions (Cl, Br and I) and copper ions have been implanted in silica glass at the same dose and at energies of the order of MeV, sequentially. The coordination structure of implanted copper atoms has been studied by X-ray absorption fine structure spectroscopy. It was found that implanted Cu atoms were coordinated with two oxygen atoms in all the as-implanted glasses. Heat treatment in air caused the formation of copper–halogen bonds without the formation of halide crystals. Further heat-treatment caused the formation of halide crystals in the glasses.

We synthesized two kinds of poly(9,9-diochtylfluorene) (PDOF) with different molecular weight distribution. One is PDOF with low weight molecular component (PDOF-l) and the other is PDOF with high molecular component (PDOF-h). The latter showed twice higher PL efficiency than the former. We investigated PL spectra and EL properties of the blended specimens of two PDOFs. The increase in PDOF-l content reduced PL intensity, conduction current at a constant voltage, and EL efficiency. We suggested the model due to excimer formation caused by the degree of freedom in motion of edge groups.

The chemical state of implanted Mg atoms has been studied in 2.48 ×1017 Mg+ ions cm-2-implanted silica glass by X-ray photoelectron spectroscopy. It was found that Mg atoms were coordinated with oxygen atoms, irrespective of the heat treatment at 900°C in an argon gas atmosphere. Mg ion implantation caused oxygen deficient species (SiOx) and increased the refractive index by about 5%. The oxygen deficient species and the refractive index change were stable against the heat treatment.

The electrical and thermal transport properties are characterized for layer-structured (ZnO)mIn2O3 (m=5 and 9) (ZmIO) ceramics of near theoretical densities. The results of the low temperature Hall effect study suggested that the InO2- layers, which have oxygen defects, determine the carrier scattering mechanism of the material, and explain the previously demonstrated two-dimensional character of the carrier transport behavior. From an adaptation of the Wiedemann–Franz law, the lattice thermal conductivity (κL) of ZmIOs at 300 K is estimated to be ~2.6 W/mK; this value is nearly one fifteenth of that for Al-doped ZnO ceramics (~40 W/mK). These results suggest that the two-dimensional structure consisting of the InZnmOm+1+ and InO2- sub-lattices gives rise to the strong electrical anisotropy and the low κL which is attributed to the reduced mean free path of the phonon, similar to artificial super-lattice materials.

Coordination structures of implanted Fe, Co, and Ni ions were studied in 1.78–2.00-MeV 5 × 1016 ions/cm2-implanted silica glasses by x-ray absorption and optical absorption spectroscopies. It was found from x-ray absorption spectra that the implanted Fe, Co, and Ni ions are coordinated by ca.3 oxygen atoms. The implanted ions dispersed in glass matrix and did not form crystals. The valence of the implanted ions was about 1.5. The Fe–O, Co–O, and Ni–O interatomic distances were 190, 191, and 192 pm, respectively. In addition, it was found from optical absorption spectra that one-fifth of implanted Co ions were present as Co2+ ions in tetrahedral symmetry.

TEM and electron diffraction investigations were performed on high-temperature and high-pressure treated polymeric C60 fullerene, prepared at 700, 773 and 800 K in the pressure range of 3-9 GPa, for one hour. A mixed phase of alternating rhombohedral lamellae and tetragonal domains is formed, even at high pressures, with the ratio of polymers being dependent on the pressure applied. At higher temperatures, 900-1173 K, and for a similar pressure range, graphitic `hard' carbon phases formed, via an interpolymer interface instability and/or shear mechanism. This phase exhibited a hardness of 10-15 GPa and a high degree of elastic recovery under indentation. Treatment times of 0.5-30 minutes for the graphitic phase showed the kinetics of graphitization to be slow (~1 h) and proceeding via cross-linked intermediates containing trapped whole C60 cages. The influence of the cross-linking resulted in hardness values up to 33.5 GPa, for a twenty-minute treatment.

The coordination structure of Cu atoms has been studied in Cu + -ion-implanted glasses and (O + + Cu + )-ion-implanted glasses at doses from 1 × 10 16 to 1 × 10 17 Cu + ions/cm 2 and from 5 × 10 15 to 5 × 10 16 O + ions/cm 2 . It was found that Cu atoms were present as Cu(I) and their coordination geometry depended on dose through the concentration of oxygen deficiency per silicon atom.

Subjecting C60 to high pressure and temperature reveals a wide range of new carbon structures ranging from polymeric to amorphous diamond-like phases. When C60 is compressed at 3 GPa and heated to 700°C it produces a form of carbon that is semimetallic and has a hardness that is approximately two-thirds that of diamond. From elastic and inelastic neutron scattering measurements and transmission electron microscopy we propose that this phase is composed of regularly warped graphite planes, much like corrugated cardboard or iron.

2 MeV Cu + ions were implanted in silica glass at doses from 1 × 10 15 to 1 × 10 17 ions/cm 2 . Cu + -ion implanted silica glass followed by heat treatment showed photoluminescence due to monovalent copper ions. The photoluminescence intensity was the highest at a dose of 1 × 10 16 Cu + ions/cm 2 in the present implantation condition. It was deduced that co-implantation of oxygen ions stabilizes the monovalent copper ions in silica glass.

Thermal relaxation of Si–O–Si bond angle has been studied in 1 MeV B + -ion, 1 MeV O + -ion and 4 MeV Ni 2+ -ion implanted silica glasses by infrared reflection and visible and near-infrared reflection spectroscopy. It is found that the change in Si–O–Si bond angle is not proportional to the change in molar volume upon annealing. It is deduced that the relaxation mechanism of Si–O–Si bond angle accompanied by little density change has an activation energy of about 100 kJ mol −1 .

Spectroscopic properties of Er3+ in Ga2S3–GeS2–La2S3 glasses are investigated on the basis of the spontaneous emission probabilities calculated by the use of the Judd–Ofelt theory and lifetime data. Frequency upconversion spectra are also measured with excitation at 800 and 980 nm. The spontaneous emission probabilities are much larger than those of the other glass systems such as oxides and fluorides. This is mainly attributed to the large refractive indices of the sulfide glasses. The quantum efficiencies of 4I11/2 and 4F9/2 levels are comparable or larger than the typical values of Er3+ in a fluoride glass. This is a consequence of the large spontaneous emission probabilities and low phonon energies of the sulfide glasses. However, the quantum efficiency of the 4S3/2 level is less than one-half of the value in the fluoride glass. The nonradiative transition probability of the 4S3/2 level is much larger than the value which is evaluated from the multiphonon relaxation theory. This suggests the presence ...

Bismuth is a half metal having anisotropic susceptibility and optical constants. Therefore, the crystal axis of bismuth particle can be oriented by magnetic torque under magnetic fields. Recently, bismuth nano-particles, which have spherical, plate-like and rod-like shapes, have been prepared by some chemical methods. Orientation of bismuth nanospheres in a viscous liquid was demonstrated by using in-situ observation system of x-ray diffraction under high magnetic field in this study. The anisotropic susceptibility determined from the orientation behavior was slightly smaller than that of the bulk bismuth crystal. We have successfully introduced oriented-bismuth nano-spheres into the transparent polymethyl metacrylate under high magnetic fields up to 8 T. The composite showed a difference in transmittance depending on the direction of propagation of light being parallel or perpendicular to the applied field, indicating an anisotropic nature of optical constants of the nano-particles. Transmission spectra, which were simulated on the nano-spheres oriented composite by rigorously coupled wave analysis (RCWA), indicated that the nano-sphere has larger anisotropy in optical constants than bulk bismuth.

We have demonstrated the formation of microdots on the surface of densified silica glass by thermal relaxation. Silica glass Was densified by approximately 4% with a hot isostatic pressing technique. A small area on the glass surface was heated to sufficiently high temperatures under an ambient pressure to induce structural relaxation by repeated irradiation of focused beam pulses from a CO 2 laser. A hump with a Gaussian shape was formed in the small area on the glass surface after the irradiation. The distribution of temperature on the irradiated surface due to the laser beam profile, optical absorption and thermal diffusion was inferred as the origin of the bump shape. This process provides us a new method of producing components for microoptics consisiting of only silica glass.

Silica glass dispersed with CuCl ultrafine particles is prepared by the implantation of 3 MeV 6 × 10 16 Cl 2+ ions cm −2 and 3 MeV6 × 10 16 Cu 2+ ions cm −2 . It is deduced that the implanted Cu ions form mainly ultrafine Cu metallic particles in the as-implanted silica glass. The ultrafine Cu metallic particles react with Cl atoms to form CuCl ultrafine particles by heating up to 900–1000°C. The number of Cu and Cl ions forming the CuCl ultrafine particles is consistent with the fluence levels of these ions. A large number of CuCl ultrafine particles can be dispersed in silica glass.

Vacuum ultraviolet (vuv) reflection spectra have been measured from amorphous ${\mathrm{SiO}}_{2}$(a-${\mathrm{SiO}}_{2}$) plates of varying densities. Two bands were observed at 10.3 and 11.4 eV in the vuv reflection spectra for as-received a-${\mathrm{SiO}}_{2}$. Upon densifying the a-${\mathrm{SiO}}_{2}$ with a multianvil-type high-pressure apparatus, both the strong band at 10.3 eV and the weaker shoulder at 11.4 eV were found to shift toward lower energies and to broaden. The shift of these bands during densification can be explained either by a unification of the extended point-dipole theory and harmonic oscillator model, or by the relationship between the band-gap energy and Si-O bond length. The broadening of the bands during densification, and thus the Si-O-Si bond-angle decrease, may be due to either the distortion of ${\mathrm{SiO}}_{4}$ tetrahedra or a widening of the distribution of rotational arrangements between connected ${\mathrm{SiO}}_{4}$ tetrahedra causing a distortion of the electronic structure. A shift of the band at 10.3 eV toward higher energy is observed upon cooling in undensified a-${\mathrm{SiO}}_{2}$, but this shift gradually disappears with increasing densification. Although the reason for the temperature dependence of band position for the undensified a-${\mathrm{SiO}}_{2}$ is not yet clear, it appears that the disappearance of this dependence with densification is related to an increase of the structural randomness of the glass.

Submillimeter wave EPR spectra have been observed for Cu 2+ spin doped calcium metaphosphate Ca(PO 3 ) 2 glass by using a pulse high magnetic field. The EPR absorption curve obtained is similar to that of the powder pattern for the usual crystalline copper compounds. The absorption curve has been simulated by assuming the line shape, angular dependence of line width and parallel and perpendicular g -values. The g -values estimated are g // =2.44±0.02 and g ⊥ =2.07±0.01. Contribution to the line width of spin-spin, spin-lattice interactions and distribution of g -value are discussed from the dependence of spin concentration and temperature on the line width.

Densification of glass is an interesting method to control optical properties of glass, such as refractive index, wavelength dispersion of refractive index, optical durability and so on, without changing its chemical composition. In this paper, densification of silica glass by means of hot isostatic pressing (HIP) and structural relaxation of the densified glass at elevated temperatures have been investigated. Two types of synthetic silica glass which have high and low OH contents were used in this experiment. The density of glass increased by about 1% after HIP treatment of 2000kgf/cm2, 1200°C, 2hrs. The refractive index (n) increased with increasing density.The wavelength dispersion of index (dn/dλ) also increased by the densification. X-ray induced absorptions at 4.8eV and 5.8eV were suppressed by the densification. The structure of the high- and low-OH glasses was stable up to about 600 and 800°C, respectively. These results suggest that the densified silica glass can be widely applied to optical use.

The synthesis of new ternary hydrides in the Mgx MnyHz-system (x:y = 1, 2, 3, or 4:1) was investigated by applying high pressures. Powder mixtures of magnesium hydride and manganese were pressed into a pellet and compressed at a pressure of 6 gigapascal by using a machine with 6–8 multi-anvils during heating up to 873 K. The resultant samples were studied by means of X-ray powder diffraction, thermogravimetry and differential thermal analysis. A new hydride of Mg3MnH5∼6 containing at least 2.4 mass% hydrogen was found, which can be indexed as a monoclinic structure with cell parameters of a = 0.8827(2) nm, b = 0.4657(2) nm, c = 0.4676(2) nm and β = 105.72(2)◦. The desorption temperature of hydrogen was determined as 603 K.

An antireflective two-dimensional subwavelength structure and a one-dimensional periodic structure with large phase retardation were fabricated on the glass surfaces by glass-imprint process. Novel low-Tg optical glasses based on bismuth phosphate and bismuth borate systems have been developed for the fabrication of these structures. These glasses had refractive indexes higher than 1.8 and deformation temperatures lower than 500 °C. Antireflective structure optimized by rigorous coupled-wave analysis was fabricated on an SiC mold having a curved surface for lens formation by using electron-beam lithography and dry etching techniques. Reflectivity at the imprinted surface relief decreased to about one-tens as compared with that at the polished surface in the visible region, and had less dependence on incident angle and wavelength. Mold shape has been optimized to fabricate one-dimensional structure with a high aspect ratio. A phase retardation of 0.23λ was observed between TE- and TM-polarized beams at 400 nm in the glass plate on both the surfaces of which one-dimensional structures were fabricated.

A one-dimensional periodic sub-wavelength structure (SWS) was fabricated on a glass plate by a glass-imprinting method. Thermal and optical properties of lithium bismuth gallium borate glasses were investigated for the development of glass suitable for the glass-imprinting method. It was found that refractive index and absorption edge energy showed additivity for glass composition and that the substitution of fluorine atoms for oxygen atoms reduced deformation temperature and increase transparency near uv region. The glass had a refractive index higher than 1.80 at 587 nm, internal transmittance higher than 80% (3 mm in thickness) at 400 nm, and deformation temperature lower than 470°C was obtained. A one-dimensional SWS with a period of 300 nm on an SiC mold was transferred to the glass surface by the glass-imprinting method, which showed the phase retardation due to form birefringence.