Annealing study on single crystal Tl-2223 superconductors
| Autor: | Bruno Morosin, Eugene L. Venturini, David S. Ginley |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
chemistry.chemical_classification
Superconductivity Controlled atmosphere Materials science High-temperature superconductivity Condensed matter physics Annealing (metallurgy) Analytical chemistry Energy Engineering and Power Technology chemistry.chemical_element Condensed Matter Physics Oxygen Electronic Optical and Magnetic Materials law.invention chemistry Meissner effect law Electrical and Electronic Engineering Inorganic compound Single crystal |
| Zdroj: | Physica C: Superconductivity. 175:241-249 |
| ISSN: | 0921-4534 |
| Popis: | We have shown that crystals in the TlCaBaCuO system are robust to anneals (oxygen, vacuum or 10%H 2 /90%N 2 ) to 500°C. Improvements in the superconducting properties, as determined from Meissner data, are observed for anneals above 300°C and suggest that as-grown crystals may not have fully equilibrated during growth despite an extended cool down cycle. There appears to be no systematic shift in T c with oxygen content in the TlO layer. Single crystal X-ray structure refinements have determined small atomic displacements which, in part, suggest the possibility of small amounts of Tl 1+ being present in the TlO layer of as-grown crystals which subsequently oxidizes during mild oxygen anneals to Tl 3+ . Hence, changes in oxygen content may not result in altered carrier concentration in the CuO layers. Further, the nature of the oxygen position in the TlO layer, as determined by the usual least-squares refinement of X-ray data, appears to be related to the amount of oxygen present in the particular sample. |
| Databáze: | OpenAIRE |
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