| Project/Area Number |
10355034
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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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 |
TAKATA Masasuke Nagaoka University of Technology, Professor, 工学部, 教授 (20107551)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Tomoichiro Nagaoka University of Technology, Research Associate, 工学部, 助手 (60313566)
野口 祐二 東京大学, 大学院・工学系研究科, 助手 (60293255)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥29,700,000 (Direct Cost: ¥29,700,000)
Fiscal Year 2000: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 1999: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1998: ¥22,000,000 (Direct Cost: ¥22,000,000)
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| Keywords | Hot spot / Oxide ion conduction / Critical current density / Oxygen sensor / Constant current characteristic / Oxygen partial pressure / Damped oscillatory current / Ultra low frequency oscillator / 定電流発生素子 / 酸素欠損 / PTCR特性 / 振動電流 / 熱伝導率 / 酸素センサー / 線材 / ペロブスカイト / イオン半径 / 混合伝導 / 高温超伝導体セラミックス / 粒界 / GdBa_2Cu_3O_<7・δ> / 温度分布 / 直流電場 |
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| Research Abstract |
When a certain voltage is applied to ReBa_2Cu_3O_<7-δ> (Re : rare-earth element) ceramic rod at room temperature, a glowing hot spot appears in the rod. This project was aimed at investigating the appearance mechanism of various functions caused by the hot spot and the feasible applications. The following results were obtained from the research.
(1) The mechanism of the hot spot migration toward the negative electrode is related to the oxide ion conduction in the hot spot.
(2) The heat treatment using the hot spot improves the critical current density of the rod.
(3) The oxygen sensor using the hot spot has an excellent sensing property and it is feasible for various uses.
(4) A hot spot appears in (Ln_<1-x>Sr_x) (Co_<1-y>Fe_y) O_<3-δ> (Ln : rare-earth element) ceramic rod. By controlling the composition of the ceramics, the sensing property of the oxygen sensor can be designed for the various uses.
(5) The fine constant current characteristic caused by the hot spot is unavailable when the rod is shorter than a certain value. A decrease in the thermal conductivity of the rod is effective for the miniaturization of the device.
(6) When a hot spot appears under lower oxygen partial pressure than a certain value, a damped oscillatory current runs through the rod. It is possible to design the oscillation frequency and the time constant of decay by controlling the thermal conduction of surrounding gas, the cross-section area of the rod, the applied voltage and the oxygen partial pressure in ambient atmosphere. An ultra low frequency oscillator can be realized by using this phenomenon.
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