The processing and properties of single grain Y-Ba-Cu-O fabricated from graded precursor powders
| Autor: | S.C. Troughton, A R Dennis, David A. Cardwell, John H. Durrell, Yunhua Shi, Susannah Speller, Wei Zhai, N A Rutter |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Superconductivity
Uniform distribution (continuous) Materials science Misorientation Metals and Alloys Analytical chemistry Green body Trapping Edge (geometry) Condensed Matter Physics Phase (matter) Materials Chemistry Ceramics and Composites Degradation (geology) Electrical and Electronic Engineering |
| Popis: | The preparation of single grain, Y-Ba-Cu-O (YBCO) bulk superconductors by top-seeded melt-growth (TSMG) usually involves precursor powders that contain a uniform distribution of the constituent YBa2Cu3O 7-δ (Y-123) and Y2BaCuO5 (Y-211) phase compounds. However, it has been observed that the concentration of Y-211 particles in the fully melt processed superconducting bulk increases significantly with distance from the seed, which results in a degradation of superconducting properties towards the edge and bottom of the sample. Here we investigate the effect of preparing bulk YBCO superconductors by TSMG using spatially graded Y-211/Y-123 precursor powder. The graded precursor bulks were prepared with a maximum composition of 40 wt% Y-211 in the vicinity of the seed, which decreased to 30 wt% and then 20 wt% towards the bottom and edge of the green body. Standard samples were melt processed from precursor powders containing 30 wt% Y-211 to enable comparison. The field trapping ability, T c and Jc, of three graded and two standard samples were investigated and compared statistically. The distribution of Y-211 particles along different growth directions of the samples was analysed, and any crystallographic misorientation was investigated. The observed distribution of Y-211 particles in YBCO is explained qualitatively by trapping/pushing theory, and its correlation with the superconducting properties of the melt processed bulk samples has been analysed. Finally, the practical feasibility of the graded technique is evaluated. © 2013 IOP Publishing Ltd. |
| Databáze: | OpenAIRE |
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