A Vacancy-Disordered, Oxygen-Deficient Perovskite with Long-Range Magnetic Ordering: Local and Average Structures and Magnetic Properties of Sr 2 Fe 1.5 Cr 0.5 O 5

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DOIResolve DOI: http://doi.org/10.1021/ic202590r
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TypeArticle
Journal titleInorganic Chemistry
ISSN0020-1669
1520-510X
Volume51
Issue4
Pages26382644; # of pages: 7
AbstractThe local and average crystal structures and magnetic properties of the oxygen-deficient perovskite Sr2Fe1.5Cr0.5O5+y were studied using powder X-ray and neutron diffraction, neutron-pair distribution function analysis, and electron energy-loss spectroscopy. This material crystallizes in the cubic Pm3̅m space group, with a = 3.94491(14) Å. The oxygen vacancies are distributed randomly throughout the perovskite-type structure, and the average coordination number of the Fe(Cr) sites is 5. Refinement of the neutron diffraction data indicates y 0.05. This is in discordance with an earlier report on a material with the same nominal composition and cell constant. Electron energy-loss Cr L2,3-edge spectroscopy shows that Cr³⁺ is present, which is also contrary to previous speculation. Neutron-pair distribution function studies show that a brownmillerite-like model involving ordered vacancies and alternating octahedral and tetrahedral coordination at the metal sites, gives a better description of the local structure out to 5 Å. A remarkable phenomenon determined by neutron diffraction in Sr2Fe1.5Cr0.5O5 is the occurrence of a long-range G-type antiferromagnetic ordering with Tc ≈ 565 K because cubic oxygen-deficient perovskites with B-site disorder usually do not undergo transitions to magnetically ordered states. The observation of long-range antiferromagnetic order and the Tc value are in accordance with previous Mössbauer spectroscopic studies.
Publication date
LanguageEnglish
AffiliationNRC Canadian Neutron Beam Centre; National Research Council Canada
Peer reviewedYes
NPARC number21268982
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Record identifierd5e8bbea-f825-4a56-b732-783dfd9ee2be
Record created2013-11-28
Record modified2016-05-09
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