Synthesis and characterisation of Sr4Fe3-xCrxO10-δ : stabilisation of n=3 Ruddlesden-Popper phases through Cr doping

Abbey Jarvis, Frank Berry, J marco, M Sanchez-Arenillas, G Sibin, Oliver Clemens, Peter Slater

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Abstract

Ruddlesden-Popper type compounds have the general formula, A n+1M nO 3n+1±x (typically A is a rare earth, alkaline earth, M is a transition metal), and are constructed of perovskite-type layers separated by rock salt type blocks. While n ​= ​1, 2 phases are typically straightforward to prepare, the synthesis of higher order (n ​> ​2) systems is difficult. In this paper we show that chromate (CrO 4 2−) doping can be exploited to stabilise new n ​= ​3 Ruddlesden-Popper systems, Sr 4Fe 3-xCr xO 10-δ: without chromate doping, a mixture of the n ​= ​2 phase Sr 3Fe 2O 7-x and perovskite-type SrFeO 3-x is obtained. This can be explained by the stabilisation of the central perovskite building block by chromate incorporation, similar to prior work on sulfate and carbonate doping in this system. The structure, and Fe/Cr oxidation states were evaluated by X-ray diffraction, 57Fe Mössbauer spectroscopy and X-ray absorption spectroscopy supporting the incorporation of Cr as CrO 4 2−. In order to examine the potential of these new systems for use as a SOFC cathode material, conductivity studies were carried out, which showed semiconducting behaviour with slightly higher conductivities than the sulfate doped counterparts.

Original languageEnglish
Article number121372
JournalJournal of Solid State Chemistry
Volume287
Issue numberJuly
Early online date14 Apr 2020
DOIs
Publication statusPublished - Jul 2020

Keywords

  • Cathode
  • Chromate
  • Ruddlesden-Popper
  • Solid oxide fuel cell

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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