Issue 16, 2016

On the relationship between chemical expansion and hydration thermodynamics of proton conducting perovskites

Abstract

In this contribution, we determine the compositional dependence of the chemical expansion and entropy of hydration of the proton conducting perovskites BaZrO3, BaSnO3, BaCeO3, and SrZrO3 by first principles phonon calculations. The calculations reveal that the cubic BaZrO3 and BaSnO3, which display the least favourable hydration enthalpies, −72 and −65 kJ mol−1, respectively, exhibit the most favourable entropies, −108 and −132 J mol−1 K−1, respectively. The strong compositional dependency of the hydration entropy primarily originates from the entropy gain upon filling the oxygen vacancy, which is closely related to the chemical expansion coefficient of oxygen vacancies, and thus the chemical expansion upon hydration. The chemical expansion coefficient of oxygen vacancies is more negative for the cubic than the orthorhombic perovskites, leading to a considerably larger chemical expansion upon hydration of the former. The calculations therefore suggest that challenges associated with chemical expansion upon hydration of BaZrO3 proton conducting electrolytes to some extent can be avoided, or reduced, by partial substitution of Zr by Ce.

Graphical abstract: On the relationship between chemical expansion and hydration thermodynamics of proton conducting perovskites

Article information

Article type
Paper
Submitted
10 Dec 2015
Accepted
26 Feb 2016
First published
01 Mar 2016
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2016,4, 5917-5924

On the relationship between chemical expansion and hydration thermodynamics of proton conducting perovskites

T. S. Bjørheim, A. Løken and R. Haugsrud, J. Mater. Chem. A, 2016, 4, 5917 DOI: 10.1039/C5TA10090A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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