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Revisiting the thermal and chemical expansion and stability of La_0.6Sr_0.4FeO_3−δ

Lookup NU author(s): Chris de Leeuwe, Dr Wenting HuORCiD, Dr Dragos Neagu, Dr Evangelos PapaioannouORCiD, Dr Stevin PramanaORCiD, Dr Brian Ray, Professor Ian MetcalfeORCiD

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Abstract

The thermal and chemical expansivity of La_1-xSr_xFeO_3-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.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.

Publication metadata

Author(s): de Leeuwe C, Hu W, Neagu D, Papaioannou EI, Pramana S, Ray B, Evans JSO, Metcalfe IS

Publication type: Article

Publication status: Published

Journal: Journal of Solid State Chemistry

Year: 2021

Volume: 293

Print publication date: 01/01/2021

Online publication date: 06/11/2020

Acceptance date: 26/10/2020

Date deposited: 10/12/2020

ISSN (print): 0022-4596

ISSN (electronic): 1095-726X

Publisher: Elsevier

URL: https://doi.org/10.1016/j.jssc.2020.121838

DOI: 10.1016/j.jssc.2020.121838

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