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Mechanical and Electrical Characteristics of Oxide Superconductor Thin Films

氧化物超导薄膜的机械和电气特性

基本信息

批准号：
07455049
负责人：
KATO Kazunori
金额：
$ 4.42万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

YBa_2Cu_3O_<7-x> (YBCO) superconducting thin film was prepared on an [111] oriented Ag film by an off-axis rf magnetron-sputtering. The [111] oriented Ag film was prepared on the (001) single-crystal natural mica substrate at the substrate temperature 200ﾟC in the argon atmosphere. The YBCO film grew with not only the strong orientation for caxis but also three-symmetrical orientation for a and b axs on the mica/Ag substrate without post-annealing. The full width at half maximum intensity of the 003 omega-rocking curve of the YBCO film was 1.52ﾟ. The optimal substrate temperature was 620ﾟC,when the partial pressure of oxygen was 1.0*10^<-2>Torr.Tc (onset) and Tc (zero) of the films were 84K and 77K respectively, according to the AC magnetic susceptibility measurements. The Jc of the film was measured by the conventional four-probe method, and Jc (J//ab) value was 1.4*10^<-1>A/cm^2 at 77K in a liquid nitrogen bath. The YBCO film showed the thickness dependence of Tc's mainly because of … More the large lattice mismatch of Ag (111) to YBCO (001). The Ag layr was found to play an important role that it became a current-path when the current value exceeded the critical current of the YBCO layr. This effect made the conductor stable. The relationships between the Jc at 77K and the strain of the YBCO films were measured to reveal the mechanical stability of the YBCO conductor, assuming the application of the conductor to the micro superconducting-coil. The Jc value of the YBCO film didn't change even when the tensile strain of 1*10^<-2> was applied. In case of compression, the Jc value increased with the increasing of strain, corresponded to the maximum, about 150% value of the Jc (strain=0), at-0.8*10^<-2>, then drastically decreased. These result ensure that the conductor can be applied to the micro-coil if the maximum strain is less than 1*10^<-2>. The stability of the Jc was also checked by dipping and taking out the film in the liquid nitrogen bath repeatedly. The surface roughness of the film increased with the repetition time due to the large thermal shrinkage and expansion of the Ag film during dipping and taking out processes, however, the Jc value was kept at the constant value even after 7 times repetition. Less

用<7-x>离轴射频磁控溅射法在[111]取向的Ag膜上制备了YBa_2Cu_3O_（YBCO）超导薄膜。在氩气保护下，衬底温度为200 ℃时，在（001）单晶天然云母衬底上制备了[111]取向的Ag薄膜。YBCO薄膜在云母/Ag衬底上生长时，不经过后退火处理，不仅具有较强的caxs取向，而且具有a轴和B轴的三对称取向。YBCO膜的003 Ω摇摆曲线的半峰强度全宽为1.52 Ω。当氧分压为1.0 × 10 ~（-3）Torr时，最佳衬底温度为620 ℃<-2>，交流磁化率测试表明，薄膜的Tc（起始）和Tc（零）分别为84 K和77 K。用传统的四探针法测量了薄膜的Jc，在液氮浴中77 K时的Jc（J//ab）值为1.4*10^<-1>A/cm ^2。YBCO薄膜表现出Tc的厚度依赖性，主要是因为 ...更多信息 Ag（111）与YBCO（001）的大晶格失配。当电流超过YBCO层的临界电流时，Ag层成为电流通路，起到了重要的作用。这种效应使导体稳定。测量了YBCO薄膜在77 K时的Jc与应变之间的关系，以揭示YBCO导体的机械稳定性，假设该导体应用于微型超导线圈。YBCO薄膜的Jc值在1 × 10 ~ 4的拉伸应变下没有变化<-2>。在压缩情况下，Jc值随着应变的增加而增加，对应于最大值，约为Jc（应变=0）值的150%，在-0.8 *10^处<-2>，然后急剧下降。这些结果确保了如果最大应变小于1*10 - 3，则导体可以应用于微线圈<-2>。还通过在液氮浴中反复浸渍和取出膜来检查Jc的稳定性。由于Ag膜在浸渍和取出过程中的大的热收缩和膨胀，膜的表面粗糙度随着重复时间而增加，然而，即使在7次重复之后，Jc值仍保持在恒定值。少