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ID 115542
Title Alternative
Evaluation of the Electronic and Local Structure of Mn in Proton-Conducting Oxide, Ca(Zr,Mn)O3-δ, To Elucidate a Direct Hydrogen-Dissolution Reaction
Author
Nakamura, Takashi Tohoku University
Watanabe, Iwao Ritsumeikan University
Doi, Takuya Tokushima University
Ina, Toshiaki Japan Synchrotron Radiation Research Institute
Nitta, Kiyofumi Japan Synchrotron Radiation Research Institute
Amezawa, Koji Tohoku University
Okuyama, Yuji University of Miyazaki
Content Type
Journal Article
Description
The protonation mechanism in Mn-doped CaZrO3 (CZM), which involves a direct hydrogen dissolution from the surrounding H2 gas, was investigated by thermogravimetry (TG) and X-ray absorption spectroscopy (XAS). The TG results implied the formation of oxygen vacancies in a H2 atmosphere. The Mn K-edge XAS spectra indicated a reduction of the Mn ions and local structure variations around the Mn ion, but the Zr K-edge spectra were independent of the surrounding atmosphere. The amount of oxygen vacancies was smaller with respect to the reduction of the Mn ions, suggesting direct dissolution of hydrogen. Unlike many typical perovskite-type proton conductors, protonation by direct dissolution of hydrogen and not hydration was the predominant reaction in Mn-doped CaZrO3. Our experimental results demonstrated that the hydration reaction was suppressed because the oxygen vacancy was stable in the distorted ZrO6 symmetry in the CaZrO3 crystal host, whereas protonation proceeded by the direct dissolution of hydrogen stabilizing near the Mn ions in the interstitial sites at the distorted MnO6 octahedron symmetry. The experimental results showed that the structural configurations around dopants play important roles in the stabilization of protons in perovskite-type CZM materials. We demonstrated a new group of proton conductors that can overcome issues with conventional proton conductors by utilizing the direct hydrogen dissolution reaction.
Journal Title
The Journal of Physical Chemistry C
ISSN
19327447
19327455
NCID
AA1217589X
AA12192210
Publisher
ACS Publications
Volume
123
Issue
26
Start Page
16034
End Page
16045
Published Date
2019-06-07
Rights
This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcc.9b03897.
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DOI (Published Version)
URL ( Publisher's Version )
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language
eng
TextVersion
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departments
Science and Technology