準安定高臨界温度超電導薄膜の表面弾性波

亚稳态高临界温度超导薄膜中的表面声波

• 批准号: 62540244
• 负责人: 秋永 正廣
• 金额: $ 1.15万
• 依托单位: Fukuoka University of Education
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62540244/
• 关键词: 高温超電導; A-15化合物

高臨界温度超電導体のA-15型Nb_3Ge薄膜及び最近発見された酸化物超電導Y-Ba-Cu-O化合物を作製し, その超電導特性を調べた.多数の超電導Nb_3Ge薄膜をR.F.スパッタ法で作成し, 電気抵抗の温度依存性を丁寧に, くわしく調べた結果, 次の2つの重要なことがわかった.(1) 常電導領域で半導体的振舞を示す試料は, percolationにより従来の記録と比べると極めて高い温度から超電導転移を開始する. 5つの試料が25Kより高いTc-onsetを示し, 最高32Kに達した. これはA-15型化合物では世界最高記録と思われる.(2) 通常の金属型を示す試料では, 明確な転移開始温度よりはるか高い温度でも大きなfluctuation効果が現れる. しかも, これらは二次元のfluctuation理論に従っている.上記現象の起源をさぐるため, SEM,EPMA等で試料の表面分析をした. その結果, 半導体的振舞を示し, しかも高Tc-onを有する試料では極めて小さな結晶粒の存在が不可欠であり, そしてこういう系ではpercolation効果が強いことがわかった. 又, fluctuation効果では, A-15相と他の相の間の結晶粒界が主役であり, この部分が2次元性を示すことが示唆された.Y-Ba-Cu-O化合物では主に(YBa_2)Cu_3O_<7-x>化合物を焼結法で作成し, その電気抵抗及び音波物性を測定した. 超電導転移温度は最高で約95Kと現在での最高水準のものが得られた. 以上の結果は第18回低温物理学国際会議で発表した.

A-15 type Nb_3Ge thin films and recently discovered superconductivity Y-Ba-Cu-O compounds were prepared and their superconductivity properties were modulated. Most of the superconducting Nb_3Ge thin films were fabricated by R.F. method, and the temperature dependence of the electrical resistance was investigated. (1)A semiconductor in the field of constant conductivity shows that the sample has a high temperature and a high conductivity. 5. Sample temperature up to 25K, Tc-onset up to 32K. A-15 compound is the highest in the world. (2)Generally, the metal type shows that the sample has a clear transition onset temperature, a high temperature, and a large fluctuation effect. The theory of two-dimensional fluctuation. The origin of the phenomenon is described above. SEM,EPMA, etc. As a result, the semiconductor vibration and dance shows that the sample has a high Tc-on, and the existence of small crystal particles cannot be ignored. In addition, due to the fluctuation effect, the crystal grain boundary between A-15 phase and other phases is mainly active, and some of them are mainly secondary active.Y-Ba-Cu-O <7-x>compounds are prepared by sintering method, and their electrical resistance and acoustic properties are measured. Superconductivity shift temperature is about 95K, and the highest level is obtained. These results were presented at the 18th International Conference on Cryophysics.