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Advanced Energy Materials Group
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Second generation (2G) Y-Ba-Cu-O coated conductor development
1997-present
The second generation (2G) wire is a fundamentally different technology
than 1G, the key element being a high-performance 1-2 micron thin YBCO
epitaxial layer deposited on a bi-axially textured oxide buffered metal
tape. The 2G
technology has two key components: (1) a textured template that enables the
growth of the biaxially aligned YBCO and (2) the superconducting YBCO layer.
Here YBCO stands for the well-known high temperature superconductor
YBa2Cu3O7 with Tc = 91 K. 2G tape is currently produced in U.S. by
American
Superconductor Corporation and SuperPower Inc. (now subsidiary of
Phillips Corp.).
 
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Structure of YBCO material |
Architecture of 2G wire produced
American
Superconductor Corporation. YBCO layer is deposited on buffered Ni alloy
tape by metal-organic deposition. |
2G research started in Brookhaven in 1997 as a
collaboration with Oxford Superconductor. The project goal was evaluation of
the ex-situ technology for large scale production of thick YBCO film with Jc
over 1 MA/cm2. An important milestone was synthesis 5 micron thick layers
with Jc over 1 MA/cm2 [1]:
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Critical current of 5 micron
(record-thickness) YBCO films synthesized at BNL in 1998. The result
validated ex-situ technology and promoted wide-spread adoption of
the process by the industry. |
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TEM study of the growth process enable
optimization of the YBCO layers properties 1997-2000. |
Our work on basic thermodynamics of the ex-situ
conversion reaction resulted in a discovery of universal law for the
reaction rate [2]. An important event was discovery of rate enhancement at
low pressure [3]. The discovery was put to practice as patented design of
sub-atmospheric reactor. Without low-pressure process the ex-situ reactors
would be extremely slow and very expensive to run.
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Significant YBCO growth rate can be achieved by
reducing total pressure during the ex-situ provessing. This result
became a basis for BNL patent # 6,794,339 |
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Sub-atmospheric reactor utilizing BNL technology
was built at Oak Ridge National Lab for pilot-production of YBCO 2G
tapes. |
Examples of application of BNL technology:
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Sub-atmospheric reactor built by Showa Electric
Wire and Cable Co., Japan. |
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Reactor operating at Institute for Machinery and
Materials, Korea. |
References
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IEEE Transactions on Applied Superconductivity
(Proceedings of Applied Supeconductivity Conference ASC 2000), vol. 11,
No 1 (March 2001), pp. 2939-2942, “Ex-situ post-deposition processing
for large area YBCO films and coated tapes”, V. F. Solovyov, H. J.
Wiesmann, L-J. Wu, Y. Zhu, and M. Suenaga.
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Applied Physics Letters, vol. 76, No 14, (April
2000), pp. 1911-1913, “Kinetics of YBa2Cu3O7 film growth by
postdeposition processing”, Vyacheslav F. Solovyov, Harold J. Wiesmann,
Li-jun Wu, Yimei Zhu, and Masaki Suenaga.
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IEEE Transactions on Applied Superconductivity
Superconductivity (Proceedings of Applied Supeconductivity Conference
ASC 1998), vol. 9, (June 1999), pp. 1467 - 1470. ”High Rate Deposition
of 5 um Thick YBa2Cu3O7 Films Using the BaF2 Ex-situ Post Annealing
Process”, V.F. Solovyov, H.J. Wiesmann, L-J. Wu, M. Suenaga and R.
Feenstra.
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Applied Physics Letters, vol. 80, No 3 (January 2002), pp. 419-421,
"Mechanisms for hetero-epitaxial nucleation of YBa2Cu3O~6.1 at the
buried precursor/SrTiO3 interface in the postdeposition reaction
process", L. Wu, V. F. Solovyov, H. J. Wiesmann, Y. Zhu, and M. Suenaga.
Last Modified: February 3, 2010
Please forward all questions about this site to:
Robert Sundling
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