L Wu et al 2003 Supercond. Sci. Technol. 16 1127 doi:10.1088/0953-2048/16/10/301
L Wu, S V Solovyov, H J Wiesmann, D O Welch and M Suenaga
Show affiliations2 µm thick epitaxial YBa2Cu3O7, YBCO, films on SrTiO3 substrates were prepared at the reaction temperatures of 725, 750 and 800 °C by the BaF2 process. The dc critical current densities of these films were found to vary by a factor of 2 at 77 K in perpendicular dc magnetic fields measured up to 1.5 T. The twin boundary spacing was essentially unchanged among these films while the size of Y2O3 precipitates in the films varied by a factor of ~5. Also, the measured ratios of the lattice parameters, a/b, of the films were surprisingly larger than those found in standard fully oxygenated YBCO. This unusual property of the films appeared to be caused by the presence of the Y2O3 precipitates which provided a strain constraint in limiting the full tetragonal-to-orthorhombic phase transformation due to the oxygenation. Differences in the degree of the constraint possibly led to the observed difference in Jc among these films.
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
Issue 10 (October 2003)
Received 1 April 2003, in final form 26 June 2003
Published 27 August 2003
L Wu et al 2003 Supercond. Sci. Technol. 16 1127
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