Chemical expansion due to hydration of proton conducting perovskite oxide ceramics
Journal article, Peer reviewed
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http://hdl.handle.net/11250/284843Utgivelsesdato
2014Metadata
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- Institutt for materialteknologi [2553]
- Publikasjoner fra CRIStin - NTNU [38525]
Sammendrag
The crystal structures of proton conducting BaZr1-xYxO3-x/2 (BZY05-BZY20) and
BaCe0.8Y0.2O2.9 (BCY20) during hydration/dehydration has been studied by in situ high
temperature X-ray diffraction and thermal analysis. A contraction / expansion of the crystal
lattice associated with dehydration / hydration was observed for all materials at elevated
temperatures and the polymorphic phase transition temperatures of BaCe0.8Y0.2O2.9 were
depressed by lowering the vapour pressure of water. A thermodynamic formalism is
introduced to describe the chemical expansion associated with the hydration of oxygen
vacancies in acceptor doped oxides. A conventional point defect model was applied to
describe the lattice strain associated with the hydration. The chemical expansion is discussed
with respect to the available volumetric data on the hydration of proton conducting oxide
materials and its likely impact on ceramic fuel cells / hydrogen separation membranes
utilising a proton conducting electrolyte.