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Title: In situ examination of oxygen non-stoichiometry in La{sub 0.80}Sr{sub 0.20}CoO{sub 3−δ} thin films at intermediate and low temperatures by x-ray diffraction

Structural evolution of epitaxial La{sub 0.80}Sr{sub 0.20}CoO{sub 3−δ} thin films under chemical and voltage stimuli was examined in situ using X-ray diffraction. The changes in lattice parameter (chemical expansivity) were used to quantify oxygen reduction reaction processes and vacancy concentration changes in lanthanum strontium cobaltite. At 550 °C, the observed lattice parameter reduction at an applied bias of −0.6 V was equivalent to that from the reducing condition of a 2% carbon monoxide atmosphere with an oxygen non-stoichiometry δ of 0.24. At lower temperatures (200 °C), the application of bias reduced the sample much more effectively than a carbon monoxide atmosphere and induced an oxygen non-stoichiometry δ of 0.47. Despite these large changes in oxygen concentration, the epitaxial thin film was completely re-oxidized and no signs of crystallinity loss or film amorphization were observed. This work demonstrates that the effects of oxygen evolution and reduction can be examined with applied bias at low temperatures, extending the ability to probe these processes with in-situ analytical techniques.
Authors:
; ;  [1] ; ; ;  [2]
  1. Oak Ridge National Laboratory, Center for Nanophase Materials Science, Oak Ridge, Tennessee 37831 (United States)
  2. Electrochemical Energy Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
22262534
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMORPHOUS STATE; CARBON MONOXIDE; LANTHANUM; LATTICE PARAMETERS; OXYGEN; STOICHIOMETRY; STRONTIUM; THIN FILMS; VACANCIES; X-RAY DIFFRACTION