Phase Evolution in Ba-(Nd,Eu,Gd)-Cu-O-Coated Conductor Films

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Journal of Materials Research

DOI:https://doi.org/10.1557/jmr.2008.0273· OSTI ID:936790

Wong-Ng, W. ^[1]; Levin, I. ^[1]; Ritter, J. ^[1]; Cook, L. P. ^[1]; Liu, G. ^[1]; Otani, M. ^[1]; Vaudin, M. ^[1]; Lucas, C. ^[2]; Diwanji, S. P. ^[2]; Feenstra, Roeland ^[3]

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1. National Institute of Standards and Technology (NIST)
2. University of Maryland
3. ORNL

Phases that are in equilibrium with BaR{sub 2}CuO{sub 6+}x (R = lanthanides and Y), such as the 'green-phase' and 'brown-phase' structural variants of BaR{sub 2}CuO{sub 5} in bulk samples, are attractive choices for flux-pinning for coated conductor applications because of the guaranteed chemical stability. In films, high-temperature x-ray diffraction studies of Ba{sub 2}RCu{sub 3}O{sub 6+}x superconductor deposited on SrTiO{sub 3} substrate using the trifluoroacetate solution method demonstrate that while BaNd{sub 2}CuO{sub 5} ('brown-phase' structure) develops at 735 C and 100 Pa{sub p{sub O2}}, neither BaGd{sub 2}CuO{sub 5} nor Ba(Nd{sub 1/3}Eu{sub 1/3}Gd{sub 1/3}){sub 2}CuO{sub 5} (both green-phase structure) form at these conditions. As a result, Ba{sub 2}(Nd{sub 1/3}Eu{sub 1/3}Gd{sub 1/3})Cu{sub 3}O{sub 6+}x in thin films is in equilibrium with the brown-phase, and Ba{sub 2}GdCu{sub 3}O{sub 6+}x is in equilibrium with Gd{sub 2}O{sub 3} in the Ba-Gd-Cu-O system, in contrast to the bulk systems. Different phase relationships in the vicinity of the Ba{sub 2}RCu{sub 3}O{sub 6+}x phase imply different phases are available for flux-pinning applications. These differences will need to be considered carefully in designing optimized superconducting coated conductors.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: OE USDOE - Office of Electric Transmission and Distribution
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 936790
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 8 Vol. 23; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
COPPER OXIDES
EQUILIBRIUM
EUROPIUM OXIDES
GADOLINIUM OXIDES
MAGNETIC FLUX
NEODYMIUM OXIDES
PHASE STUDIES
SUPERCONDUCTORS