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Traditionally, the stuffing model has been used to describe stress generation in chemically strengthened glass. Nevertheless, the associated unrealistic conditions, including an imaginary volume expansion and its suppression in an adiabatic closed system, inhibit a thorough understanding of the process. In this study, we propose a thermodynamic model in an isothermal open system to enable ion exchange without an imaginary volume expansion. We derive a fundamental equation and verify it using atomistic images obtained by Raman spectroscopy and nuclear magnetic resonance. This study paves the way for further atomistic design and development of strengthened glasses. [ABSTRACT FROM AUTHOR]

We have shown that typical amorphous chalcogenides, As2S3 bulk with a thickness of 50–100 μm and fiber with a diameter of 100 μm, can be bent by controlling the orientation of linearly polarized light. The bending of the bulk and fiber with thickness and diameter comparable to the optical penetration depth is efficiently generated by irradiation with a light of 2.33 eV, corresponding to the optical bandgap of amorphous As2S3. We have evinced that the bent phenomena of the amorphous As2S3 bulk and fiber are dominantly due to photo-induced anisotropy, fluidity, and optical torque effects. Then, the optical torque when bending occurred on the As2S3 fiber was quantitatively evaluated as ~ 10−7 N‧m in the case of 20 W/cm2 irradiation. The bending of the As2S3 bulk glass and fiber due to the temperature rise by bandgap light irradiation is not dominant. [ABSTRACT FROM AUTHOR]

We have fabricated a rechargeable photo-chemical battery using ion-hole conducting AgAsS2 films. An asymmetrically-electroded Al/AgAsS2/SnO2 yields photocurrents and upon illumination it is concomitantly charged up. When the illumination is stopped, the stack discharges electricity into an external circuit. This photo-charging and discharging phenomenon is attributed to a photo-chemical modification of Ag-ion distribution in amorphous AgAsS2. [ABSTRACT FROM AUTHOR]

Oxide glasses generally have low thermal conductivity due to their disordered structures. Here, a fabrication method to provide them with high thermal conductivity while retaining their optical transparency is proposed. It consists of dispersing ∼20 μm MgO crystals in a glass matrix and matching their refractive indexes to prevent the decrease of the oxide glass optical transparency due to light scattering. The dispersion of the MgO crystals increased the thermal conductivity of the original glass by ∼50% and the new glass still exhibited optical transparency. Such MgO-dispersed glass could be successfully used in thermal management applications requiring both transparency and formability. [ABSTRACT FROM AUTHOR]

Chemically strengthened glass has become essential in our daily lives and the demand is rapidly increasing in a variety of fields. However, the conventional cutting process is not applicable because of its tough layer with the compressive stress. To achieve higher-throughput production of the glass, we report spatially selective weakening of the compression layer by CO 2 laser scanning and provide its visualization by Raman mapping. We demonstrate cutting the scanned glass without shattering using a typical scribing wheel. Finally, we discuss the improvement in processability from the viewpoint of microscopic structures by means of thermal analysis and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

We investigated the Pockels effect in polycrystalline materials consisting of highly oriented polar fresnoite-type Sr2TiSi2O8 fabricated using perfectly surface-crystallized glass-ceramics (PSCGCs). The chemical composition of the precursor glass was shown to significantly affect the crystallized texture, e.g., the crystal orientation and appearance of amorphous nanoparasites in the domains, resulting in variations in the Pockels constants. Single crystals exhibiting spontaneous polarization possessed large structural anisotropy, leading to a strong dependence of the nonlinearoptical properties on the direction of polarized light. This study suggests that variations in the Pockels constants (r13 and r33) and tuning of the r13/r33 ratio can be realized in PSC-GC materials. [ABSTRACT FROM AUTHOR]

We have synthesized spinon thermal conductivity materials in Sr- Cu- O system by glass-ceramics technique. The materials are promising for active control of thermal energy in microelectronic devices because of high and anisotropic thermal conduction, its controllability, and electric insulation. Nevertheless, research on these materials has been limited to that concerning theoretical perspectives and investigation of physical properties using large single crystals. In this study, we adopt glass-ceramics technique to synthesize these materials: We prepared melt-quenched multicomponent oxides including SrO and CuO, and checked its glass-forming ability and crystallization behaviors by heating. As a result, we have found that SrCuO2 and Sr14 Cu24 O41, known as the spinon thermal conductivity materials, are synthesized using SrO- CuO-- Li2 O-- Al2 O3-- Ga2 O3 system. This synthesis process for the system will provide practical application of the spinon thermal conductivity materials. [ABSTRACT FROM AUTHOR]

We prepared SrCuO 2 film by radio-frequency magnetron sputtering on silica glass and have investigated structure change induced by super-band-gap light. An X-ray diffraction pattern shows that the as-sputtered film is composed of (001)-oriented SrCuO 2 nanothick crystals belonging to tetragonal system, i.e., the layer-type SrCuO 2 . Raman-scattering spectra show that irradiation of high-power super-band-gap laser light onto the film gives rise to structure change into orthorhombic system, i.e., the chain type SrCuO 2 , which is known to exhibit high, anisotropic thermal conductivity due to spin interaction. A mechanism of the structure change is discussed in terms of photoexcitation and heating process. [ABSTRACT FROM AUTHOR]

Abstract: Oxy-chalcogenide glasses with compositions of xGeO2–(100− x)GeS2, where 0⩽ x ⩽100mol%, have been prepared and studied in terms of their structures and optical properties. X-ray fluorescence spectroscopy shows that Ge:S ratio can deviate from GeS2 by ∼10at.%, depending critically upon the preparation conditions. Raman scattering spectroscopy suggests that stoichiometric GeO2–GeS2 glasses have a heterogeneous structure in the scale of 1–100nm. The optical gaps are nearly constant at 3.0–3.5eV for glasses with 0⩽ x ⩽80mol% and abruptly increase to ∼6eV in GeO2. This dependence suggests that the optical gap is governed by GeS2 clusters, which are isolated and/or percolated. Composition-deviated glasses appear as orange and brown, and these glasses seem to have more inhomogeneous structures. [Copyright &y& Elsevier]

Abstract: Photo-induced changes in GeO2 glass have been studied in terms of its optical and structural properties. Band-gap excitation gives rise to modifications in mid-gap optical absorption and photo-luminescence spectra. It also produces electron-spin signals at g ≃1.995 and 2.008. Raman-scattering spectrum becomes sharper, X-ray diffraction patterns show a disappearance of a crystalline peak, and the illuminated surfaces expand. These observations can be accounted for by assuming bond transformations from rutile-like to defective quartz-like structures and/or from small to large rings. These photo-induced changes in GeO2 are discussed in comparison with those in SiO2 and GeS2. [Copyright &y& Elsevier]

Abstract: Macroscopic and microscopic changes in sputtered GeO2 films induced by band-gap light from an ArF excimer laser have been studied. When irradiated at 1atm, the film thickness increases, surface-roughness increases, refractive-index decreases, hygroscopic enhancements, and Ge–O–Ge distance increases. Irradiations in vacuum make these changes smaller or undetectable. These photo-induced changes are discussed from phenomenological and structural viewpoints, and compared with characteristics in GeO2–SiO2 and GeS2 films. [Copyright &y& Elsevier]

Noninvasive and site-selective temperature sensing is required in biology and advanced medicine. Recently, we proposed a new concept for temperature sensing, which is based on afterglow and optically-stimulated luminescence [Sci. Rep. 10 , 2242 (2020)]. Here we assessed the thermal sensitivity of afterglow zirconia and clarified the potential of this material as probe phosphor by thermoluminescence measurements. The evaluated sensitivity value of the zirconia was 10 %/K, which was higher than typical materials used in luminescent thermometers. Therefore, the prepared zirconia is a great candidate as a harmless and biocompatible sensing probe. [ABSTRACT FROM AUTHOR]

We have fabricated perfectly-surface-crystallized glass-ceramics (PSC-GCs) consisting of polar frenoite-type Sr 2 TiSi 2 O 8 by different crystallization-process conditions, i.e., isothermal treatment at 880 °C for 72 h and 960 °C for 1 h, and have examined their Pockels effect in this study. The PSC-GCs obtained by the lower-temperature process exhibited the Pockels coefficients, i.e., r 13 ∼ 3.0 pm/V and r 33 ∼ 2.4 pm/V, and the coefficients exceeded the reported values of the PSC-GCs with Sr 2 TiSi 2 O 8 phase. The improvement of Pockels effect is attributed to the higher crystal-orientation, which is provided by the lower-temperature condition. [ABSTRACT FROM AUTHOR]

Silicate glass has been used for long time because of its advantages from material's viewpoint. In this paper, we report the observation of Pockels effect by Mach-Zehnder interferometer in polycrystalline ceramics made from a ternary silicate glass via crystallization due to heat-treatment, i.e., glass-ceramics. Since the silicate system is employed as the precursor, merits of glass material are fully utilized to fabricate the optical device component, in addition to that of functional crystalline material, leading us to provide an electro-optic device, which is introducible into glass-fiber network. [ABSTRACT FROM AUTHOR]

We investigated the long-lasting photoluminescence (LLP) properties in a commercial zirconia powder with a monoclinic system after thermal treatment at different temperatures. Clear-blue photoluminescence and LLP were observed in the zirconia without emissive dopants subjected to thermal treatment at 1400 °C. Decay curve measurements revealed a pronounced, visually observable bluish LLP that lasted for ~ 10 h at moderate temperature. Based on spectroscopic observation and electron spin resonance results, a possible origin of the LLP is discussed. [ABSTRACT FROM AUTHOR]

Atomic bonding structures in xGeO2–(100-x)GeS2 glasses have been studied through structural and chemical experiments. Atomic force microscope images in alkali-etched samples with x = 80 mol % show nano-scale dips, which are ascribable to isolated GeS2 clusters. Transmission electron microscope images and small angle X-ray scattering patterns suggest that the glass with x ≈50 has pronounced heterogeneous structures in nanoscales. Composition dependence of an etching rate exhibits a characteristic change at x = 60, which can be interpreted as a percolation threshold of tetrahedral GeS4 units. These results support a nanostructure model for the oxy-chalcogenide glass. [ABSTRACT FROM AUTHOR]

Photoluminescence and electron-spin resonance in nano-structured GeO2–GeS2 glasses have been studied. With an increase in the GeO2 content from 0 to 80 mol %, a luminescence peak blue-shifts from 1.3 to 2.1 eV in photon energy, which is more prominent than an increase in the optical gap from 3.4 to 3.6 eV. Dark and photoinduced electron-spin signals become maximal at around an intermediate composition 50GeO2–50GeS2. It is difficult to interpret these composition variations using the charged defect model proposed for chalcogenide glasses. [ABSTRACT FROM AUTHOR]

Study on visible light response of photocatalytic materials is very important research area for future energy society. Generally, in conventional photocatalysts, visible light response is provided by defect introduction. This phenomenon is based on formation of trap level between valence and conduction band. In our previous report, we have already succeeded in observing the photocatalytic activity of TiO 2 crystallized glass. Since glass-based material is suitable for industrial use, crystallized glass is expected to be a novel bulk photocatalyst with high productivity if we provide visible light response ability to TiO 2 crystallized glass. In this study, we tried the defect introduction to TiO 2 crystallized glass and investigated the photocatalytic activity under visible light irradiation. As a result, we have demonstrated water splitting by TiO 2 crystallized glass with Ti 3+ defect under visible light irradiation for the first time. [ABSTRACT FROM AUTHOR]

Energy storage technology is crucial for a sustainable society, and its realisation strongly depends on the development of materials. Oxide glass exhibits high durability. Moreover, the amorphous structure of the glass without periodic ordering demonstrates excellent formability and controllability, thus enabling a large-scale production. These factors provide impetus for the development of new materials for thermal management applications. As vanadium dioxide (VO 2 ) with a strongly correlated electron system exhibits a structural phase transition, leading to a large heat of transition. Therefore, VO 2 demonstrates immense potential as a phase change material (PCM). This study reports the fabrication of VO 2 -dispersed glass and examines its potential as a new latent heat storage material, which can be applied for massive PCM heat storage applications.