| Project/Area Number |
10650822
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
無機工業化学
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
KOMATSU Takayuki Nagaoka University of Technology, Faculty of Engineering, Professor, 工学部, 教授 (60143822)
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| Co-Investigator(Kenkyū-buntansha) |
BENINO Yasuhiko Nagaoka University of Technology, Faculty of Engineering, Research Assistant, 工学部, 助手 (90283035)
デミトロフ ベセリン 長岡技術科学大学, 工学部, 助教授 (50303178)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Tellurite glass / Bismuth glass / low phonon energy / Glass transition / Heat capacity / Enthalpy relaxation / Fragility / Structural relaxation / 構造暖和 |
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| Research Abstract |
The purpose of this study is to clarify the mechanism of unique structural relaxation of optical functional TeOィイD22ィエD2- and BiィイD22ィエD2OィイD23ィエD2-based glasses with low phonon energies through measurements of viscosity, heat capacity and Vickers hardness in the glass transition region. The following results were obtained.
1) the thermal stability against crystallization in RィイD22ィエD20-MO-TeOィイD22ィエD2 glasses (R=Li,Na, K, M=Mg, Ba, Zn) increases with the combination between oxides showing large different optical basicities ( e.g. KィイD22ィエD2O-MgO, LiィイD22ィエD20-BaO).
2) the heat capacity changes at the glass transition in KィイD22ィエD20-MgO-TeOィイD22ィエD2 glasses are extremely large, I.e. ΔCィイD2PィエD2A=45J/molK, meaning that the breaking of the network structure and rearrangements among network units occur easily in these glasses. This feature is appeared in a rapid decrease of Vickers hardness at the glass transition.
3) the activation energies for enthalpy relaxation in TeOィイD22ィエD2-based glasses are 900〜1250kJ/mo, which are much large compared with silicate glasses, and those for viscous flow are 500〜750kJ/mol, giving the fragility values of around 60. The decoupling between enthalpy relaxation and viscous flow is clearly observed in both TeOィイD22ィエD2- and BiィイD22ィエD2OィイD23ィエD2-based (such as BiィイD22ィエD20ィイD23ィエD2-BィイD22ィエD20ィイD23ィエD2) glasses.
4) both TeOィイD22ィエD2- and BiィイD22ィエD2OィイD23ィエD2-based glasses belong to the category of fragile glass-forming systems.
5) both systems show a unique structural relaxation at the glass transition, but the present study demonstrates that it is possible to fabricate glasses having high potential for technical applications.
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