Crystallographic and magnetic structure of the perovskite-type compound BaFeO2.5 : unrivaled complexity in oxygen vacancy ordering

Research output: Contribution to journalArticle

Authors

  • Oliver Clemens
  • Melanie Gröting
  • Ralf Witte
  • J. Manuel Perez-mato
  • Christoph Loho
  • Frank J. Berry
  • Robert Kruk
  • Kevin S. Knight
  • Horst Hahn

Colleges, School and Institutes

Abstract

We report here on the characterization of the vacancy-ordered perovskite-type structure of BaFeO2.5 by means of combined Rietveld analysis of powder X-ray and neutron diffraction data. The compound crystallizes in the monoclinic space group P21/c [a = 6.9753(1) Å, b = 11.7281(2) Å, c = 23.4507(4) Å, β = 98.813(1)°, and Z = 28] containing seven crystallographically different iron atoms. The coordination scheme is determined to be Ba7(FeO4/2)1(FeO3/2O1/1)3(FeO5/2)2(FeO6/2)1 = Ba7Fe[6]1Fe[5]2Fe[4]4O17.5 and is in agreement with the 57Fe Mössbauer spectra and density functional theory based calculations. To our knowledge, the structure of BaFeO2.5 is the most complicated perovskite-type superstructure reported so far (largest primitive cell, number of ABX2.5 units per unit cell, and number of different crystallographic sites). The magnetic structure was determined from the powder neutron diffraction data and can be understood in terms of “G-type” antiferromagnetic ordering between connected iron-containing polyhedra, in agreement with field-sweep and zero-field-cooled/field-cooled measurements.

Details

Original languageEnglish
Pages (from-to)5911-5921
JournalInorganic Chemistry
Volume53
Issue number12
Early online date5 Jun 2014
Publication statusPublished - 16 Jun 2014

Keywords

  • Neutron Powder Diffraction, X-ray Powder Diffraction, BaFeO2.5, Ba2Fe2O5, Magnetic Structure Determination, Mössbauer spectroscopy, DFT calculations