A57Fe Mössbauer Study ofREBa2Fe3O8+wTriple Perovskites with Varied Oxygen Content (RE=Dy, Er, and Y)

J. Lindén*, A. Kjekshus, P. Karen, J. Miettinen, M. Karppinen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

Abstract

REBa2Fe3O8+wphases (RE=Dy, Er, and Y) with a varied oxygen content (-0.25<w<0.10 in general, widest forRE=Dy, narrowest forRE=Er) have been obtained by quenching from controlled atmospheres. The triple-perovskite-type structure is adopted for these phases, with two crystallographically different iron atoms, tetragonal abovew≈-0.15 and orthorhombic below that oxygen content. The valence and spin states of iron are investigated using57Fe Mössbauer spectroscopy. At room temperature, an antiferromagnetic ordering is observed for all values ofw. Six- and five-coordinated Fe3+,S=52environments are distinguished in the Mössbauer spectra and their occupancies forw=0 are in the exact structural ratio of these two coordinations. Forw>0, tetravalent iron (S=2) accompanies the extra oxygen atoms at the (originally) square-pyramidal Fe site, whereas divalent iron (S=2) accompanies the oxygen vacancies formed in the octahedral Fe site whenw<0. The latter splits into two components, the intensities of which correspond to the fractions of five- and four-coordinated iron with a random distribution of meridial oxygen vacancies in an octahedron.

Original languageEnglish
Pages (from-to)168-175
Number of pages8
JournalJournal of Solid State Chemistry
Volume139
Issue number1
DOIs
Publication statusPublished - Aug 1998
MoE publication typeA1 Journal article-refereed

Keywords

  • Rare earth barium iron oxides; triple perovskites; Mössbauer spectroscopy; Fe valence and spin state; statistics of; antiferromagnetic order of.

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