Two- and three-dimensional connectivity and current distribution in YBa2Cu3Ox-coated conductors
Two- and three-dimensional connectivity and current distribution in YBa2Cu3Ox-coated conductors
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YBa2Cu3Ox 涂层导体的二维和三维连通性和电流分布
DOI：
10.1063/1.1855414
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发表时间：
2005
影响因子：
4
通讯作者：
J. Schwartz
中科院分区：
文献类型：
--
作者：
D. C. V. D. Laan;M. Dhallé;H. J. Eck;A. Metz;B. T. Haken;H. Kate;L. Naveira;M. Davidson;J. Schwartz
YBa_2Cu_3O_x_sYBCO_d涂层导体的微观结构强烈地依赖于YBCO层的沉积方法和厚度。这封信显示了真空沉积和溶液生长层之间的晶粒连通性的明确定性差异如何对临界电流密度sJcd的空间分布产生直接影响。脉冲激光沉积的YBCO导体通常具有柱状晶粒结构，导致二维电流网络，如磁光成像所示。因此，它们的传输Jc在从50 mm到5 mm的长度尺度上变化很大，即使在与宏观电流平行的缺陷处也会发生电流抑制。相比之下，金属有机沉积样品中较厚的YBCO涂层具有层状结构，导致三维电流path. Magneto-optically，这是从样品范围内的屏蔽电流推导出来的，而传输实验揭示了Jc的小得多的空间变化。这些结果是令人鼓舞的非真空生产的YBCO涂层导体的进一步发展，因为这样的三维系统本质上是更“宽容”的局部缺陷。
The microstructure of YBa2Cu3Ox sYBCOd-coated conductors depends strongly on the deposition method and thickness of the YBCO layer. This letter shows how the clear qualitative difference in grain connectivity between vacuum-deposited and solution-grown layers has direct consequences for the spatial distribution of the critical current density sJcd. Pulsed-laser-deposited YBCO conductors usually have a columnar grain structure that results in a two-dimensional current network, as demonstrated with magneto-optical imaging. Consequently, their transport Jc varies considerably on length scales from 50 mm up to 5 mm, with current suppression occurring even at defects that run parallel to the macroscopic current. In contrast, the thicker YBCO coatings in metalorganic-deposited samples have a layered structure, leading to a three-dimensional current path. Magneto-optically, this is deduced from sample-wide shielding currents, while transport experiments reveal much smaller spatial variations in Jc. These results are encouraging for the further development of nonvacuum produced YBCO-coated conductors, since such three-dimensional systems are inherently more “forgiving” of local defects.