Solution Processed Lanthanum Zirconium Oxide as a Primary Barrier Layer for High Ic Coated Conductors
- ORNL
- American Superconductor Corporation, Westborough, MA
High-quality lanthanum zirconium oxide (La{sub 2}Zr{sub 2}O{sub 7} or LZO) films have been deposited and processed on Ni-W substrates using a sol-gel processing approach. It has been demonstrated that crack-free coatings with thicknesses up to 100 nm can be processed in a single step, while thicker coatings (200-225 nm) were processed using a multiple coating and annealing process. Using simulated metalorganic deposition (MOD)-YBa{sub 2}Cu{sub 3}O{sub 7-:{angstrom}} (YBCO) processing conditions, the barrier properties of the sol-gel LZO coating with a thickness of 120 nm were found to be comparable to that of the standard 3-layer buffer stack deposited using physical vapor deposition. Secondary ion mass spectroscopy depth profile analysis of LZO films annealed in oxygen-18 shows that LZO effectively stops the diffusion of Ni within the first 80-100 nm. Using MOD processes, a CeO{sub 2} cap layer and superconducting YBCO layer were deposited on sol-gel LZO/Ni-W. For the first time, using such an all-solution conductor architecture, a critical current (I{sub c}) of 140 A/cm with a corresponding critical current density (J{sub c}) of 1.75 MA/cm{sup 2} has been demonstrated. Using a very thin Y{sub 2}O{sub 3} seed layer ({approx}10 nm) deposited by electron beam evaporation; improved texture quality in the LZO layers has been demonstrated. The performance of the LZO deposited on these samples was evaluated using a sputtered CeO{sub 2} cap layer and MOD YBCO layer. Critical currents of up to 255 A/cm (3.2 MA/cm{sup 2}) with 0.8-{micro}m-thick YBCO films have been demonstrated, comparable to the performance of films grown using physical vapor deposited yttria stabilized zirconia as a barrier layer. Similar experiments using an MOD-CeO{sub 2} cap layer and MOD-YBCO layer yielded critical currents of 200 A/cm (2.5 MA/cm{sup 2}) with 0.8-{micro}m-thick YBCO films.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- OE USDOE - Office of Electric Transmission and Distribution
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 965814
- Journal Information:
- Journal of Materials Research, Vol. 21, Issue 4; ISSN 0884-2914
- Country of Publication:
- United States
- Language:
- English
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