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  4. A TEM study of Ni interfaces formed during activation of SOFC anodes in H 2 : Influence of grain boundary symmetry and segregation of impurities
 
research article

A TEM study of Ni interfaces formed during activation of SOFC anodes in H 2 : Influence of grain boundary symmetry and segregation of impurities

Jeangros, Q.
•
Aebersold, A.B.
•
Hébert, C.
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2016
Acta Materialia

The electrochemical properties of a solid oxide fuel cell depend on many parameters, including – on the anode side – the connectivity of the Ni network and the segregation of impurities at active points. In this work, advanced scanning transmission electron microscopy techniques are employed to assess 1) the influence of the symmetry of NiO/NiO grain boundaries on the percolation of the Ni phase after activation and 2) the segregation of impurities at these new Ni interfaces that form during NiO reduction. Automated crystal orientation mapping in the transmission electron microscope reveals that coherent NiO twin boundaries remain intact during reduction, while NiO grains separated by an incoherent boundary detach from each other when reducing to Ni. Small Ni domains twinned with respect to the larger Ni grains are also observed to form during reduction of the NiO phase. Energy-dispersive X-ray spectroscopy reveals that Al and Si impurities, which are present in the raw materials, may block electrochemically active points of the anode by segregating in the form of a glassy film at the interfaces/surfaces that appeared during activation. This oxidised film supports Ni nanoparticles that precipitated from volatile Ni hydroxide.

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Type
research article
DOI
10.1016/j.actamat.2015.10.028
Web of Science ID

WOS:000367630500044

Author(s)
Jeangros, Q.
Aebersold, A.B.
Hébert, C.
Van Herle, J.
Hessler-Wyser, A.
Date Issued

2016

Published in
Acta Materialia
Volume

103

Start page

442

End page

447

Subjects

Solid oxide fuel cells

•

Transmission electron microscopy

•

Diffraction

•

Energy-dispersive X-ray spectroscopy

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
SCI-STI-JVH  
LSME  
Available on Infoscience
February 19, 2018
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/144919
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