Long-range ordering in the Bi{sub 1-x}Ae{sub x}FeO{sub 3-x/2} perovskites: Bi{sub 1/3}Sr{sub 2/3}FeO{sub 2.67} and Bi{sub 1/2}Ca{sub 1/2}FeO{sub 2.75}
- Laboratoire CRISMAT-ENSICAEN, Bd du Marechal Juin-14050 CAEN cedex (France)
- EMAT, University of Antwerp, Groenenborgerlaan 171, B 2020 ANTWERPEN (Belgium)
Two-ordered perovskites, Bi{sub 1/3}Sr{sub 2/3}FeO{sub 2.67} and Bi{sub 1/2}Ca{sub 1/2}FeO{sub 2.75}, have been stabilized and characterized by transmission electron microscopy, Moessbauer spectroscopy and X-ray powder diffraction techniques. They both exhibit orthorhombic superstructures, one with a{approx}b{approx}2a{sub p} and c{approx}3a{sub p} (S.G.: Pb2n or Pbmn) for the Sr-based compound and one with a{approx}b{approx}2a{sub p} and c{approx}8a{sub p} (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 [FeO{sub x}]{sub {infinity}} layer, suggesting that Bi{sub 1/3}Sr{sub 2/3}FeO{sub 2.67} and Bi{sub 1/2}Ca{sub 1/2}FeO{sub 2.75} 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 Moessbauer 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 Bi{sub 1/3}Sr{sub 2/3}FeO{sub 2.67} and a smooth reversible transition between 590 and 650 K for Bi{sub 1/2}Ca{sub 1/2}FeO{sub 2.75}. - Graphical abstract: Complex long-range ordering of Bi/Ae cations and oxygen/vacancies consisting of 12-fold and 32-fold enlargement of the perovskite unit cell is observed in Bi{sub 1/3}Sr{sub 2/3}FeO{sub 2.67} and Bi{sub 1/2}Ca{sub 1/2}FeO{sub 2.75}, respectively.
- OSTI ID:
- 21212038
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 10; Other Information: DOI: 10.1016/j.jssc.2008.04.047; PII: S0022-4596(08)00301-0; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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