Long-range ordering in the Bi1−xAexFeO3−x/2 perovskites: Bi1/3Sr2/3FeO2.67 and Bi1/2Ca1/2FeO2.75
| Autor: | C. Lepoittevin, Nicolas Barrier, M. Hervieu, Sylvie Malo, N. Nguyen, G. Van Tendeloo |
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| Rok vydání: | 2008 |
| Předmět: |
Mössbauer effect
Chemistry Physics Condensed Matter Physics Electronic Optical and Magnetic Materials Inorganic Chemistry Crystallography X-ray crystallography Scanning transmission electron microscopy Materials Chemistry Ceramics and Composites Orthorhombic crystal system Physical and Theoretical Chemistry High-resolution transmission electron microscopy Superstructure (condensed matter) Powder diffraction Perovskite (structure) |
| Zdroj: | Journal of solid state chemistry |
| ISSN: | 0022-4596 |
| DOI: | 10.1016/j.jssc.2008.04.047 |
| Popis: | Two-ordered perovskites, Bi1/3Sr2/3FeO2.67 and Bi1/2Ca1/2FeO2.75, have been stabilized and characterized by transmission electron microscopy, Mossbauer spectroscopy and X-ray powder diffraction techniques. They both exhibit orthorhombic superstructures, one with a≈b≈2ap and c≈3ap (S.G.: Pb2n or Pbmn) for the Sr-based compound and one with a≈b≈2ap and c≈8ap (S.G.: B222, Bmm2, B2mm or Bmmm) for the Ca-based one. The high-resolution transmission electron microscopy (HRTEM) images evidence the existence of one deficient [FeOx]∞ layer, suggesting that Bi1/3Sr2/3FeO2.67 and Bi1/2Ca1/2FeO2.75 behave differently compared to their Ln-based homolog. The HAADF-STEM images allow to propose a model of cation ordering on the A sites of the perovskite. The Mossbauer analyses confirm the trivalent state of iron and its complex environment with three types of coordination. Both compounds exhibit a high value of resistivity and the inverse molar susceptibility versus temperature curves evidence a magnetic transition at about 730 K for the Bi1/3Sr2/3FeO2.67 and a smooth reversible transition between 590 and 650 K for Bi1/2Ca1/2FeO2.75. |
| Databáze: | OpenAIRE |
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