Study of the Structure Defects and the Degradation of High-T_c Superconducting Oxide Y-Ba-Cu-O by High Resolution Electron Microscopy

高温超导氧化物Y-Ba-Cu-O结构缺陷及降解的高分辨率电子显微镜研究

• 批准号: 63420046
• 负责人: NAGAKURA Sigemaro
• 金额: $ 24.96万
• 依托单位: Nagaoka University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63420046/
• 关键词: High-T_c Superconducting Oxide; Y-Ba-Cu-O; Bi-Sr-Ca-Cu-O; Structure Defects; Degradation by Water Vapor; High Resolution Electron Microscopy; Displacement Wave Model; Superspace Group Analysis; Y系酸化物高温超伝導体; Y系酸化物の水蒸気による分解; Bi系酸化物高温超伝導体; Bi系酸化物の

In this research project, structures of the Y-series and Bi-series of high-T_c superconducting oxides were studied mainly by high resolution electron microscopy. The following results were obtained.1. Study of YBa_2Cu_3O_<7-y> It was found that in crystals prepared by sintering planar defects are formed as a result of the invasion of CuO layer between BaO layers, and that the axial ratio b/a fluctuates from place to place, indicating inhomogeneous distribution of oxygen concentration. The degradation of this oxide by water vapor was also studied. The result showed that the decomposition starts at first from the separation of Ba from BaO layer and the final products are BaCO_3 formed on the specimen surface, Y(OH)_3 formed on the crystal boundary and CuO formed by the reconstruction of CuO layers.2. Study of Bi-Sr-Ca-Cu-0 High resolution electron microscopic observations found that characteristic incommensurate modulation in the crystal is formed along the b-axis as a result of the peri … More odic segregation of Bi atoms and this strains the crystal severely. Based on the observation a structure model was constructed assuming displacement waves with longitudinal and transverse components. This model explained well the distribution of electron diffraction intensities. Studies were also made for crystals in which a part of Bi was replaced by Pb. The replacement was found to reduce the internal strain remarkably. A displacement wave model similar to the above explained the electron diffraction intensities. With increase of Pb a phase with longer period (incommensurate period 7b_0-8b_0; b_0 is the fundamental period) was found to appear other than the phase without Pb replacement (period 4.8b_0). When a part of Ca was replaced by Y, the incommensurate period decreases gradually with increasing amount of Y, and commensurate phases with period 4b_0 and 8b_0 are formed also. Apart from these studies an explanation of the incommensurate structure was made on the basis of superspace group theory. The superspace group N^<Bbmb> or N^<Bb2b> was derived from the extinction rule. This gave the displacement wave and the probability of atom occupancy. Comparison of the obtained results with the observed led a satisfactory result. Less

本研究项目主要用高分辨电子显微镜研究了高T_c超导氧化物的Y系列和Bi系列的结构。取得了以下研究成果：1.对YBa2Cu3O7-y&gt的研究发现，在烧结晶体中，由于BaO层之间CuO层的侵入而形成了平面缺陷，轴向比b/a随位置波动，表明氧浓度分布不均匀。还研究了水蒸气对该氧化物的降解作用。结果表明：1.分解反应首先从BaO层和BaO层分离开始，最终产物为样品表面生成的BaCO3、晶界上生成的Y(OH)3和CuO层重构生成的CuO。对高分辨电子显微镜观察的研究发现，由于周向…，晶体中沿b轴形成了特征的无公度调制更多的奇偏析的铋原子和这严重的应变晶体。在观测的基础上，假定位移波具有纵向和横向分量，建立了结构模型。该模型很好地解释了电子衍射强度的分布。对铅取代部分铋的晶体也进行了研究。更换后可显著降低内应力。类似于上述的位移波模型解释了电子的衍射强度。随着铅含量的增加，出现一个周期较长的相(无公度周期7b_0-8b_0；b_0为基本周期)，而不是没有铅替代的相(周期为4.8b_0)。当部分Ca被Y取代时，无公度周期随着Y含量的增加而逐渐减小，并形成周期为4b_0和8b_0的公度相。除了这些研究外，还用超空间群理论解释了无公度结构。超空间群N^&lt；bbmb&gt；或N^&lt；bb2b&gt；是从消光规则导出的。这给出了位移波和原子占据的几率。将所得结果与观测结果进行了比较，得到了满意的结果。较少

项目成果

宮川勝己,佐々木純,柳田和男,弘津禎彦,山本直紀,長倉繁麿: "起伝導酸化物YBa_2Cu_3O_<7-y>の高温度雰囲気における構造変化" 日本金属学会平成2年度春期講演大会. (4月). (1990)

Katsumi Miyakawa、Jun Sasaki、Kazuo Yanagida、Yoshihiko Hirotsu、Naoki Yamamoto、Shigemaro Nagakura：“高温气氛中导电氧化物YBa_2Cu_3O_<7-y>的结构变化”1990年日本金属学会春季会议（4（1990）。

Y.Hirotsu,N.Yamamoto,O.Tomioka,K.Miyagawa,Y.Nakamura,Y.Inoue,S.Nagakura,Y.Iwai M.Takata: "Modulated Structure of Bi-Based High-Tc Superconducting Oxides" Proc.2nd International Symposium on Superconductivity(November 14-17,Tsukuba)印刷中. (1990)

Y. Hirotsu、N. Yamamoto、O. Tomioka、K. Miyakawa、Y. Nakamura、Y. Inoue、S. Nagakura、Y. Iwai M. Takata：“双基高温超导氧化物的调制结构”Proc。第二届国际超导研讨会（11 月 14 日至 17 日，筑波）现已印刷（1990 年）。

Y. Hirotsu, Y. Nakamura, N. Yamamoto, Y. Murata, O. Tomioka, M. Takata, S. Nagakura: "Structure and Defects of the Superconducting Oxides YBa_2Cu_3O_<7-delta> Studied by Electron" Proc. JIMIS-5: Non-Equilibrium Solid Phase of Metals and Alloys, Suppl. Tra

Y. Hirotsu、Y. Nakamura、N. Yamamoto、Y. Murata、O. Tomioka、M. Takata、S. Nagakura：“电子研究的超导氧化物 YBa_2Cu_3O_<7-delta> 的结构和缺陷”Proc。

N. Yamamoto, Y. Hirotsu, Y. Nakamura, S. Nagakura: "Superspace Group Analysis of the Modulated Structure in Superconductor Bi-Sr-Ca-Cu-O." Japanese Journal of Applied Physics, Vol.28 (1989), L598-L601.

N. Yamamoto、Y. Hirotsu、Y. Nakamura、S. Nagakura：“超导体 Bi-Sr-Ca-Cu-O 中调制结构的超空间群分析”。

Y.Hirotsu,N.Yamamoto,O.Yomioka,K.Miyagawa,Y.Nakamura,Y.Inoue,S.Nagakura,Y.Iwai,M.Takata: "Modulated Structures of BiーBased HighーTc Superconducting Oxides" Proc.2nd International Symposium on Superconductivity(November 14ー17,Tsukuba). (1990)

Y. Hirotsu、N. Yamamoto、O. Yomioka、K. Miyakawa、Y. Nakamura、Y. Inoue、S. Nagakura、Y. Iwai、M. Takata：“双基高温超导氧化物的调制结构”Proc .第二届国际超导研讨会（11月14-17日，筑波）（1990年）。