Processing and Properties of Bulk Y鈥揃a鈥揅u鈥揙 Superconductors Fabricated by Top Seeded Melt Growth from Precursor Pellets Containing a Graded CeO2 Composition

详细信息    查看全文

• 作者：Wei Zhai ; Yunhua Shi ; John H. Durrell ; Anthony R. Dennis ; Zhiwei Zhang ; David A. Cardwell
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：February 4, 2015
• 年：2015
• 卷：15
• 期：2
• 页码：907-914
• 全文大小：537K
• ISSN：1528-7505

文摘

The existence of a zone containing a low concentration of Y₂BaCuO₅ (Y-211) phase particles in the vicinity of the seed in single grain, bulk Y鈥揃a鈥揅u鈥揙 (YBCO) superconductors fabricated by the top seeded melt growth (TSMG) technique has been reported, suggesting the presence of low intrinsic magnetic flux pinning, and hence reduced trapped field, in this region of the sample. The possibility of introducing additional pinning centers in the vicinity of the seed in single grain YBCO, therefore, may be effective in improving the applied magnetic properties of these technologically important materials. Single grain, bulk YBCO superconductors fabricated from precursor pellets containing a graded CeO₂ composition have been prepared corresponding to a secondary phase content of 2 wt % CeO₂ beneath the seed and 1 wt % CeO₂ at the outer, 鈥淯鈥?shape cross-section, of the sample. The resulting graded single grain YBCO superconductors exhibit enhanced trapped field compared to standard YBCO superconductors fabricated by TSMG from precursor pellets containing purely 1 wt % CeO₂. The influence of CeO₂ content on the microstructure, growth process, and superconducting properties of bulk, single grain YBCO superconductors fabricated by TSMG has been investigated and used to explain the increased trapped field ability of the graded composition.