Characterization of natural and artificial low-angle boundaries in YBCO TSMG samples
| Autor: | Herbert C. Freyhardt, B. Bringmann, A. Leenders, M. P. Delamare, H. Walter |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
010302 applied physics
Superconductivity Materials science Energy-dispersive X-ray spectroscopy Energy Engineering and Power Technology chemistry.chemical_element Yttrium Welding Condensed Matter Physics Microstructure 01 natural sciences Copper Electronic Optical and Magnetic Materials Characterization (materials science) law.invention chemistry law 0103 physical sciences Grain boundary Electrical and Electronic Engineering Composite material 010306 general physics |
| Zdroj: | Physica C: Superconductivity. 329:160-177 |
| ISSN: | 0921-4534 |
| DOI: | 10.1016/s0921-4534(99)00454-2 |
| Popis: | Since several years, technical applications of bulk HTS YBCO superconductors are of growing interest. However, shapes of HTS tiles needed for complex applications require the joining of two or more single-domain monoliths. The welding technique leads to the formation of a low-angle grain boundary and then requires a high connectivity between two adjacent single-domain materials. This study was devoted to the characterization of the microstructure and the superconducting properties of natural and artificial low-angle grain boundaries. The natural grain boundary formed during the multi-seeded melt growth (MSMG) process exhibits a non-uniform microstructure during the growth. An energy dispersive spectroscopy (EDS) analysis carried out across the grain boundaries always reveals a depletion of copper and an accumulation of yttrium. Mechanical joining of two single-domain monoliths leads to the formation of an artificial grain boundary. This kind of joining was performed either without or with a welding agent, i.e., YbBa 2 Cu 3 O 7− x (Yb-123). The first method leads to a good connectivity between welded Y-123 platelets. In contrast, the control of the mechanical welding process with a welding agent is more difficult. At 940°C, Yb-123 decomposes into Yb 2 BaCuO 5 , BaCuO 2 and CuO. This decomposition deteriorates the superconducting properties between two adjacent domains. |
| Databáze: | OpenAIRE |
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