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TitleOxygen deficiency, stacking faults and calcium substitution in MOD YBCO coated conductors
Publication TypeJournal Article
Year of Publication2013
AuthorsTalantsev, E.F., Wimbush S.C., Strickland N.M., Xia J.A., D'Souza P., Storey J.G., Tallon J.L., Ingham B., Knibbe R., and Long N.J.
JournalIEEE Transactions on Applied Superconductivity
Date Published2013
ISSN10518223 (ISSN)
KeywordsCalcium, Calcium substitution, Copper compounds, Critical current density (superconductivity), Defects, Hole concentration, Hole-doping, Loading, Metal-organic, Microstructural defects, MOD-YBCO, Overdoped, Oxygen, Oxygen annealing, Oxygen deficiency, Oxygen loading, Phase diagrams, Stacking faults, Superconducting cuprates, YBCO coated conductors, yttrium, Yttrium barium copper oxides
AbstractThe variation in transition temperature Tc with oxygen deficiency or calcium substitution in Y1-xCaxBa 2Cu3O7-δ (YBCO) is a well-known manifestation of the generic hole-doping phase diagram governing the superconducting cuprates. Less well understood is the role that microstructural defects can play in determining hole doping. We have investigated the formation of Y124-type stacking faults in metal-organic deposited (MOD) YBCO coated conductors and shown that these defects also act to reduce the hole concentration in YBCO. With low stacking-fault density, Tc can be as low as 89 K when fully oxygen loaded and can increase to a maximum of 94 K when partially unloaded. The presence of stacking faults limits the degree to which fully oxygen loaded YBCO can be overdoped. The critical current density J c is optimized by full oxygen loading but with a moderate density of stacking faults. We have demonstrated substitution of calcium for yttrium in YBCO by modification of the MOD precursor resulting in an increase in hole concentration and consequent decrease in Tc. Jc is initially depressed by calcium substitution but partially recovers upon incorporation of a moderate density of stacking faults. © 2002-2011 IEEE.

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