Oxygen 'disorder' and the structures of high-Tc superconductors by neutron powder diffraction
| Autor: | A. W. Hewat, E. A. Hewat, P. Bordet, J.-J. Capponi, C. Chaillout, J. Chenavas, J.-L. Hodeau, M. Marezio, P. Strobel, M. Francois, K. Yvon, P. Fischer, J.-L. Tholence |
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| Rok vydání: | 1989 |
| Předmět: |
chemistry.chemical_classification
Superconductivity Materials science Valence (chemistry) High-temperature superconductivity General Computer Science Neutron diffraction law.invention Crystallography chemistry law Orthorhombic crystal system Inorganic compound Perovskite (structure) Monoclinic crystal system |
| Zdroj: | IBM Journal of Research and Development. 33:220-227 |
| ISSN: | 0018-8646 |
| DOI: | 10.1147/rd.333.0220 |
| Popis: | All of the high-T/sub c/ perovskite superconductors appear to show disorder of certain oxygen atoms. In (La,Sr)/sub 2/CuO/sub 4/ and perhaps also in YBa/sub 2/Cu/sub 3/O/sub 7/ this is associated with a structural transition. The Bi and Tl superconductors, for which the authors have neutron structural data on four different phases, also how oxygen disorder which may be associated with valence fluctuations. In Tl/sub 2/Ba/sub 2/CuO/sub 6/, electron holes are created by the absence of 1/8 of the atoms in the TlO plane, producing a marked superstructure. However, this material is not superconducting if the superstructure is well ordered, with an orthorhombic (strictly monoclinic) structure. The T/sub c/ appears to depend on the disorder of the superstructure to produce a pseudotetragonal metric in which the oxygen atoms within the TlO plane are distributed over four equivalent sites about the center of the Tl square. |
| Databáze: | OpenAIRE |
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