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

在该研究项目中，主要通过高分辨率电子显微镜研究了高-T_C超导氧化物的Y系列和双重系列的结构。获得以下结果1。 YBA_2CU_3O__ <7-Y>的研究发现，在通过烧结的平面缺陷制备的晶体中，由于BAO层之间的CuO层入侵而形成，并且轴向比率B/A从到位的位置波动，表明氧气浓度不均匀分布。还研究了水蒸气对这种氧化物的降解。结果表明，分解首先是从BA与BAO层的分离开始的，最终产物是在样品表面形成的BACO_3，在晶体边界上形成的Y（OH）_3，由CuO层的重建形成CUO。 BI-SR-CA-CU-0高分辨率电子显微镜观察结果的研究发现，由于骨膜的更高含量，BI原子的较高odic隔离及其晶体严重菌株，沿B轴形成了晶体中的特征性不一致的调节。基于观察结果，构建了结构模型，假设具有纵向和横向成分的位移波。该模型很好地解释了电子衍射强度的分布。还对晶体进行了研究，其中一部分被PB代替了BI。发现替换可大大减少内部应变。与上述相似的位移波模型解释了电子衍射强度。随着PB的增加，发现较长的时期（不稳定的周期7b_0-8b_0; b_0是基本周期）出现在没有PB替代的相位（周期4.8B_0）之外。当CA的一部分被Y取代时，不一致的周期随着Y量的增加而逐渐减少，并且还形成了与周期4b_0和8b_0的相称相。除了这些研究外，根据超空间群体理论对不一致的结构进行了解释。 SuperSpace组N^<BBMB>或N^<bb2b>是从扩展规则得出的。这给出了位移波和原子占用率的概率。将获得的结果与观察到的结果进行比较导致令人满意的结果。较少的

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, 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。

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,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）。

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”。