Jones, Camille Y. and Wu, Jian and Li, LiPing and Haile, Sossina M. (2005) Hydrogen content in doped and undoped BaPrO3 and BaCeO3 by cold neutron prompt-gamma activation analysis. Journal of Applied Physics, 97 (11). Art. no. 114908. ISSN 0021-8979 http://resolver.caltech.edu/CaltechAUTHORS:JONjap05
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Proton uptake in undoped and Y-doped BaPrO3 has been measured by cold neutron prompt-gamma activation analysis, and compared to the proton uptake in Gd-doped BaCeO3, as determined by the same technique. The conventional proton incorporation model of perovskites in which oxygen ion vacancies, generated by the introduction of the trivalent dopant onto the tetravalent perovskite site, are filled with hydroxyl groups upon exposure of the sample to H2O containing atmospheres, predicts that the proton concentration in such materials should be no greater than the dopant concentration. In contradiction to this model, the proton concentration in BaPr1–xYxO3 after humidification is as much as three times greater than the dopant concentration, and even undoped samples contain a high concentration of protons. Moreover, x-ray photoemission spectra suggest that the Pr oxidation state is lowered upon hydration. In contrast, BaCe0.9Y0.1O3 shows a typical hydrogen concentration, of close to 90% of the yttrium concentration. The results are interpreted in terms of the variable valence of Pr, which can become reduced from the 4+ to the 3+ oxidation state upon exposure to water, and effectively behaves as a self-dopant within the structure.
|Additional Information:||©2005 American Institute of Physics (Received 20 July 2004; accepted 4 April 2005; published online 31 May 2005) Funding for this work was provided by the Department of Energy, Office of Energy Efficiency and Renewable Energy. The authors are additionally grateful to Dr. Rick Paul sNISTd and David Michalak sCaltechd for assistance with PGAA and XPS experiments, respectively.|
|Subject Keywords:||barium compounds; neutron activation analysis; doping; X-ray photoelectron spectra; solvation; oxidation|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
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|Deposited On:||18 Feb 2006|
|Last Modified:||26 Dec 2012 08:46|
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