Publishing type：Research paper (scientific journal)   Publisher：Ceramic Society of Japan  

DOI： 10.2109/jcersj2.24115

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Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

It was reported that a bismuth iron borate amorphous oxide glass, 10Fe3O4–45Bi2O3–45B2O3, exhibits a low electronic conductivity (σ) of ∼10−8 S/cm at room temperature. In this study, we have found that fluorine addition drastically enhances its σ to six orders of magnitude higher σ of ∼10−2 S/cm in a 21Fe3O4–4BiF3–30Bi2O3–45B2O3 glass. Additionally, it is experimentally confirmed that a high electron density of ∼1017 cm−3 at 400 °C is achieved. X-ray photoemission spectroscopy reveals Bi–F, Fe–F, and B–F bondings, supporting the fluorine substitution at oxygen sites. The fluorine-added bismuth iron borate glass would be expected in semiconductor applications such as a thermistor operating at 25–400 °C.

DOI： 10.1063/5.0232888

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

We report novel oxide glasses that are compatible with ultra‐high Young's modulus (∼150 GPa) and a small coefficient of thermal expansion (∼5.0 ppm/K). These glasses were prepared using a conventional melt‐quenching technique. The viscosity–temperature relation provides the reshaping temperature for the stiff and less dilated oxide glasses. The origin of the ultra‐high Young's modulus is the inclusion of Y ₂ O ₃ as well as five‐ and six‐coordinated alumina oxide and Ta ₂ O ₅ , which has a large ionic packing ratio due to higher oxygen coordination numbers. On the other hand, the small thermal expansion coefficient originates from including Ta ₂ O ₅ and SiO ₂ with large dissociation energy due to strong bonds.

DOI： 10.1111/jace.19995

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10854-024-12542-3

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Other Link： https://link.springer.com/article/10.1007/s10854-024-12542-3/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Optical fibers of a typical chalcogenide glass, As₂S₃, can be sharply bent only by sideward irradiation of polarized light. The bending direction depends on the polarization; the fiber bends in the forward/backward directions of light propagation for bandgap light that is linearly-polarized orthogonal/parallel to the fiber axis. A reciprocity law between the intensity and the exposure time holds, which suggests that thermal effects are irrelevant. Alternatively, the bending appears to arise from photo-induced optomechanical forces and fluidity. This phenomenon could be developed to a photo-manipulation method of chalcogenide-glass fibers, promising for all-optical switching/modulation devices working at infrared wavelengths.

DOI： 10.35848/1882-0786/ad09ee

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Other Link： https://iopscience.iop.org/article/10.35848/1882-0786/ad09ee/pdf

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

Several glassy oxide semiconductors exhibit large electron mobilities; however, these oxides may not be considered environmentally friendly because of their toxicity. Herein, we report on the electrical conduction of iron oxide-containing bismuth sesquioxide borate glasses that are not toxic and show ohmic transport in the temperature range of 100–400 °C. The dominant carrier is the electron, which is revealed by the signs of Hall and Seebeck coefficients, without sign anomalies. The Hall mobility is ∼0.1 cm2/(V s), and the carrier density is ∼6 × 1015 cm−3 at 400 °C. The Seebeck coefficient is approximately −500 μV/K at 388 °C. The carriers might be generated by charge transfer between Fe2+ and Fe3+ substituted in the glass, and they exhibit thermally activated hopping-type electronic conduction. The oxide glass can be used as a glass thermistor for a temperature range of 100–400 °C.

DOI： 10.1063/5.0149523

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jnoncrysol.2022.122017

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

The well‐known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta ₂ O ₅ contents in an MgO–Ta ₂ O ₅ –Al ₂ O ₃ –SiO ₂ –B ₂ O ₃ glass system using a conventional melt‐quenching method are revealed. The essential oxides of Al ₂ O ₃ and Ta ₂ O ₅ are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al ₂ O ₃ /[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al ₂ O ₃ /MgO. According to magic‐angle spinning‐nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.

DOI： 10.1111/jace.18863

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jace.18863

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.optmat.2022.113074

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Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

We examined the relationship between optical properties and structures of 5s ² -type cations such as Sn ²⁺ - and Sb ³⁺ -containing borate and borosilicate glass. Linear evolutions were observed for the compositional dependences of density, glass transition temperature, refractive index, and photoelastic constant in visible transparent oxide glasses. The structural information was provided using vibrational spectroscopy to elucidate polyhedral units of the borate and borosilicate systems. A weak ligand field around a Sn ²⁺ close to tetrahedral borate unit, which is supported by applying density functional theory calculation, might lead to a blueshift of optical bandgap keeping small photoelastic constant and high refractive index.

DOI： 10.35848/1347-4065/ac87e2

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac87e2/pdf

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jnoncrysol.2021.120720

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Presentation type：Poster presentation  

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Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (general)  

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Presentation type：Poster presentation  

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Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (invited, special)  

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Presentation type：Oral presentation (invited, special)  

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Presentation type：Oral presentation (invited, special)  

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Presentation type：Oral presentation (general)  

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