Simultaneous Cation-Substitution Effects on Superconducting Properties of Sm-Ba-Cu Oxide Superconductors

合成了阳离子化学计量比的SmBa_2Cu_3O_<7-d>（Sm-123）样品，以排除阳离子非化学计量相和第二相粒子的钉扎对J_c峰值效应的贡献。通过拉曼散射、粉末X射线衍射和Rietveld分析，成功地得到了阳离子化学计量比的Sm-123样品。氧含量为7-d_1 =6.84的Sm-123样品在77 K和1 T下的J_c值为10 kA/cm ^2，表现出峰值效应。另一方面，7-d=6.89和6.95的样品没有表现出峰值效应。在Sm-123超导体中，氧耗尽区是导致钉扎峰效应的主要原因用高分辨透射电子显微镜（LA_HRTEM）研究了Y-Ba-Cu-O苏佩体中峰效应的来源 ...更多信息 导电体还开发了一种用于LA-HRTEM观测中能量色散X射线分析的试样制造方法。采用熔体生长技术在不同氧分压下合成了Y-Ba-Cu-O超导块材。用LA-HRTEM测量了Y_2BaCuO-（Y-211）颗粒的晶粒尺寸分布和孪晶间的晶界距离。在低磁场下，Y-211颗粒与Y-123基体之间的界面面积与J_c值成正比。在强磁场下，孪晶间的界面距离与J_c值成反比。结果表明，孪晶界面附近的贫氧区对峰效应的产生起钉扎作用，而Y-211颗粒与Y-123基体之间的界面对峰效应的产生的钉扎作用非常有限。制定了一个反向出现峰值效应的热处理程序，验证了材料设计指导原则的正确性。少

Cation-stoichiometric is SmBa_2Cu_3O_<7-d>(Sm-123) samples were synthesized to exclude contribution of pinning at particles of cation-nonstoichiometric phases and second phases to peak effect of J_c The samples were annealed in different conditions and had various oxygen contents. From results of Raman scattering, powder x-ray diffractometry and Rietveld analysis, cation-stoichiometric Sm-123 samples were successfully obtained. A Sm-123 sample with oxygen content, 7-d,=6.84 exhibited peak effect and its J_c value at 77 K and 1 T was 10kA/cm^2. On the other hand, samples with 7-d=6.89 and 6.95 did not exhibit the peak effect Contrary to the previous reports, it was concluded that oxygen depleted regions would work for the pinning to exhibit the peak effect in Sm-123 superconductors.A novel transmission electron microscopy technique termed as large area high-resolution transmission electron microscopy(LA_HRTEM) was developed to identyfy unknown origin of the peak effect in Y-Ba-Cu-O supe … More rconducting bulks. A specimen fabrication method was also developed for energy dispersive x-ray analyses in LA-HRTEM observations. Superconducting bulks of Y-Ba-Cu-O were synthesized by a melt growth technique under varied oxygen partial pressure. Distributions of grain sizes for Y_2BaCuO-(Y-211) particles and inter-twin-boundary-distances were measured utilizing LA-HRTEM. Area of the interface between the Y-211 particles and the Y-123 matrix was found to be proportional to the J_c value at low magntic fields. On the other hand, the inter-twin-boundary-distance was inversely proportional to the J_c value at high magnetic fields. From these results, oxygen depleted regions in the vicinity of the twin boundaies would work for pinning to exhibit the peak effect, while contribution of the interface between Y-211 particles and Y-123 matrix to the pinning for the appearance of the peak effect was very limited. A heat treatment program was developed to appear the peak effect reversively and confirmed the validity of the guiding principle for designing mateirals. Less