T-c enhancement by partial substitution of Ca in superconducting YbBa2Cu4O8 epitaxial films prepared by coating-pyrolysis process

Citation
Y. Yajima et al., T-c enhancement by partial substitution of Ca in superconducting YbBa2Cu4O8 epitaxial films prepared by coating-pyrolysis process, J CRYST GR, 229(1), 2001, pp. 365-368
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF CRYSTAL GROWTH
ISSN journal
0022-0248 → ACNP
Volume
229
Issue
1
Year of publication
2001
Pages
365 - 368
Database
ISI
SICI code
0022-0248(200107)229:1<365:TEBPSO>2.0.ZU;2-6
Abstract
Ca-substituted epitaxial YbBa2Cu4O8 (Yb124) films were prepared by a coatin g-pyrolysis process to enhance the superconducting transition temperature. The Ca-doped Yb124 films showed higher T-c values, e.g., 81K, by AC-suscept ibility measurement for the film with a nominal composition of Yb :Ca: Ba: Cu = 0.95 : 0.05: 2: 4. These films contained a small proportion of Ca-dope d YbBa2Cu3Oy [Yb(Ca)123] as an impurity phase. However, these high T, value s should be attributed not to Yb(Ca)123 but to (Yb1-xCax)Ba2Cu4O8, because both the slow- and fast-cooled films showed almost the same T-c values, tha t are higher than those of the Ca-free films. (C) 2001 Elsevier Science B.V . All rights reserved.