Hot spot phenomenon originated from the grain boundary of high-Tc superconducting ceramics and the application

高温超导陶瓷晶界热点现象及其应用

• 批准号: 10355034
• 负责人: TAKATA Masasuke
• 金额: $ 19.01万
• 依托单位: Nagaoka University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10355034/
• 关键词: 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; 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

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.

当将一定的电压应用于RebA_2CU_3O_ <7-udu_du__（回复：稀土元件）陶瓷杆时，杆中会出现发光的热点。该项目旨在研究由热点和可行应用引起的各种功能的外观机制。 （1）热点向负电极迁移的机制与热点的氧化物离子传导有关。（2）使用热点的热处理改善了杆的关键电流密度。（3）使用热点的氧气传感器具有出色的敏感性，并且_（4）是可行的。 （co_ <1-y> fe_y）o_ <3-δ>（ln：稀土元件）陶瓷棒。通过控制陶瓷的组成，可以设计用于各种用途的氧气传感器的灵敏度特性。（5）当杆的短时，由热点引起的细恒定电流特性是不可用的。杆的热导率的降低对于设备的微型化是有效的。（6）当热点出现在较低的氧气下压之下，而不是一定值时，该死的振荡电流会通过杆穿过。可以通过控制周围气体的热传导，杆的横截面面积，施加的电压和氧气压在环境气氛中来设计振荡频率和衰减的时间常数。可以通过使用此现象来实现超低频振荡器。