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

de Leeuwe, Christopher and Hu, Wenting and Neagu, Dragos and Papaioannou, Evangelos I. and Pramana, Stevin and Ray, Brian and Evans, John S.O. and Metcalfe, Ian S. (2021) Revisiting the thermal and chemical expansion and stability of La0.6Sr0.4FeO3−δ. Journal of Solid State Chemistry, 293. 121838. ISSN 0022-4596 (https://doi.org/10.1016/j.jssc.2020.121838)

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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.

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