Progress towards a low-cost commercial coated conductor
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Progress towards a low-cost commercial coated conductor Suresh Annavarapu, Nguyet Nguyen, Sky Cui, Urs Schoop, Cees Thieme, Martin W. Rupich, Thomas Kodenkandath, Darren Verebelyi, Wei Zhang, Xiaoping Li, Qi Li, Mariappan Paranthaman1, Amit Goyal2, Claudia Cantoni3, Matthew M. Kowalewski2 and Fred A. List2. Corporate Research & Development, American Superconductor, Westborough , MA 01581, U.S.A. 1 Chemical & Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A. 2 Metals & Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A. 3 Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A. ABSTRACT YBCO films prepared from metal trifluoroacetate (TFA) precursors on oxide-buffered textured non-magnetic substrates have achieved performance levels equaling that on oxide buffered textured Ni substrates. Critical current densities of 0.7 MA/cm2 to 1.0 MA/cm2 have been achieved in 0.4 µm thick YBCO films on short-length of CeO2/YSZ/Y2O3/Ni/Ni-13wt%Cr substrates. High-quality epitaxial buffers comprising a Ni layer, Y2O3 seed, YSZ barrier and CeO2 cap layers have been deposited over meter long tapes of deformation textured Ni and Ni13%Cr using reel-to-reel processes. High-performance TFA-based YBCO films have been deposited on 0.1 m to 0.3 m lengths of these oxide buffered substrates using reel to reel processes. Critical current densities up to 1.0 MA/cm2 have been achieved in 0.4 µm thick YBCO films on CeO2/YSZ/Y2O3/Ni substrates. Using multiple coats of the metal trifluoroacetate precursors, thicker YBCO films have been demonstrated on oxide buffered substrates. Critical currents in excess of 100A/cm-width have been achieved for 1.2 µm - 1.6 µm thick YBCO films on short lengths of CeO2/YSZ/Y2O3/Ni substrates. INTRODUCTION We have investigated a potentially low-cost process for YBCO coated conductors. The process consists of solution-based deposition of the superconducting YBCO layer onto a vapor-deposited oxide buffer layer on a textured non-magnetic alloy substrate. In this paper, we review the current status of this work, including short length samples and extensions to a continuous reel-toreel process.
EXPERIMENTAL YBCO Deposition: The YBCO films were deposited on continuous lengths of buffered substrates by metalorganic deposition using trifluoroacetate (TFA) precursors as described in [1]. On short E7.7.1
samples, the YBCO films were deposited from the same precursor solution by spin-coating. Conversion of continuous lengths of precursor film to the superconducting phase was carried out in a reel-to-reel system, while shorts were converted in a static furnace. Buffer Layer Deposition: Gd2O3 and Y2O3 seed layers were deposited on continuous lengths of deformation textured substrates by metalorganic deposition and electron-beam deposition respectively, using techniques described previously [1,2]. The YSZ barrier and CeO2 cap layers were deposited on continuous lengths of seed layers by magnetron sputtering on reel-to-reel equipment at Amer
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