X-ray investigation of the incommensurate modulated structure of Bi2+xSr3-xFe2O9+ delta

Autor:	H. Leligny, Olivier Perez, B. Raveau, Ph Labbe, D. Grebille, Daniel Groult
Rok vydání:	1995
Předmět:	Diffraction Superconductivity Strontium Inorganic chemistry Iron oxide chemistry.chemical_element Crystal structure Condensed Matter Physics Bismuth chemistry.chemical_compound Crystallography chemistry Ferrite (magnet) General Materials Science Single crystal
Zdroj:	Journal of Physics: Condensed Matter. 7:10003-10014
ISSN:	1361-648X 0953-8984
DOI:	10.1088/0953-8984/7/50/030
Popis:	A single crystal of the Bi 2212 iron oxide Bi2+xSr3-xFe2O9+ delta , exhibiting an incommensurate modulation, was characterized. The modulated structure was refined from X-ray diffraction data including satellite reflections up to the second order and using the four-dimensional formalism. A substitutional modulation (Bi for Sr3-x) occurs over the Sr3-x sites neighbouring the BiO layers whereas the other Sr3-x sites, between the FeO2 layers, are only occupied by strontium atoms. This leads to a bismuth-rich ferrite of chemical formula Bi2.4Sr2.6Fe2O9+ delta Different types of coordination are observed both for the iron atoms and for the strontium atoms on the substituted sites. Evidence for anomalies in the Bi positions was found; these anomalies were located in the BiO layers, suggesting a possible static disorder of bismuth atoms. Moreover. This effect would be closely related to the variation of the iron coordination. Finally, a comparison with the related superconductor compound Bi2Sr2CaCu2O8+ delta is given.
Databáze:	OpenAIRE
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