In situ examination of oxygen non-stoichiometry in La0.80Sr0.20CoO3−δ thin films at intermediate and low temperatures by x-ray diffraction
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AbstractStructural evolution of epitaxial La0.80Sr 0.20CoO3-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. © 2014 AIP Publishing LLC.
CitationBiegalski MD, Crumlin E, Belianinov A, Mutoro E, Shao-Horn Y, et al. (2014) In situ examination of oxygen non-stoichiometry in La0.80Sr0.20CoO3−δ thin films at intermediate and low temperatures by x-ray diffraction. Applied Physics Letters 104: 161910. Available: http://dx.doi.org/10.1063/1.4873542.
SponsorsResearch was supported (M.D.B., A.B., and S.V.K.) by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division. This research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. This work was also supported in part by NSF CBET 08-44526, DOE (SISGR DE-SC0002633), King Abdullah University of Science and Technology and King Fahd University of Petroleum and Minerals in Dharam, Saudi Arabia for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM. E. Mutoro was supported from the German Research Foundation (DFG research scholarship).
JournalApplied Physics Letters