Revisiting the thermal and chemical expansion and stability of La0.6Sr0.4FeO3−δ

Christopher de Leeuwe, Wenting Hu, Dragos Neagu, Evangelos I. Papaioannou, Stevin Pramana, Brian Ray, John S.O. Evans, Ian S. Metcalfe

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Abstract

The thermal and chemical expansivity of La1-xSrxFeO3-δ (x ​= ​0.4) was measured using in situ powder neutron and synchrotron X-ray diffraction at temperatures between 932 ​K and 1170 ​K and oxygen partial pressures, PO2, between 10−19 ​bar and 0.1 ​bar, giving a wide range of oxygen non-stoichiometry from δ = 0.05 to 0.22. Changes in δ were measured independently using gas analysis. This PO2 and temperature range covers the material's use as a chemical looping oxygen carrier, a sensor material and in solid oxide fuel cells. Thermal and chemical expansivities were found to be dependent on the oxygen non-stoichiometry, δ. For δ ​< ​0.2 and T ​= ​932–1050 ​K, the linear thermal expansivity was 5.72(4) ​× ​10−5 ​Å/K and the linear chemical expansivity was 0.144(9) Å per unit change in δ. For δ ​> ​0.2 and T ​= ​973–1173 ​K, the linear thermal expansivity increases to 6.18(8) ​× ​10−5 ​Å/K. For δ ​> ​0.2, the linear chemical expansivity varies with both δ and temperature.

Original languageEnglish
Article number121838
Number of pages9
JournalJournal of Solid State Chemistry
Volume293
Early online date6 Nov 2020
DOIs
Publication statusPublished - 31 Jan 2021

Keywords

  • chemical expansivity
  • chemical looping
  • membrane
  • mixed ionic electronic conductor
  • SOFC cathode
  • strontium-doped lanthanum ferrite
  • thermal expansivity

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