Tetrahedral chain order in the Sr2Fe2O5 brownmillerite

Hans D'Hondt, Artem M. Abakumov, Joke Hadermann, Anna S. Kalyuzhnaya, Marina G. Rozova, Evgeny V. Antipov, Gustaaf Van Tendeloo

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)

Abstract

The crystal structure of the Sr2Fe2O5 brownmillerite has been investigated using electron diffraction and high resolution electron microscopy. The Sr2Fe2O5 structure demonstrates two-dimensional order: the tetrahedral chains with two mirror-related configurations (L and R) are arranged within the tetrahedral layers according to the - L - R - L - R - sequence, and the layers themselves are displaced with respect to each other over 1/2[111] or 1/2[111̄] vectors of the brownmillerite unit cell, resulting in different ordered stacking variants. A unified superspace model is constructed for ordered stacking sequences in brownmillerites based on the average brownmillerite structure with a = 5.5298(4)Å, b -15.5875(12)Å, c = 5.6687(4)Aring;, and (3 + 1)-dimensional superspace group I2/m(0βγ)0s, q = βb* + γc*, 0 ≤ β ≤ 1/2, 0 < y < 1.

Original languageEnglish
Pages (from-to)7188-7194
Number of pages7
JournalChemistry of Materials
Volume20
Issue number22
DOIs
Publication statusPublished - 25 Nov 2008
Externally publishedYes

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