Proton diffusion mechanisms in the double perovskite cathode material GdBaCo2O5.5 : A molecular dynamics study

Mécanismes de diffusion des protons dans le matériau double pérovskite GdBaCo2O5.5 : Étude de dynamique moléculaire

Fabien Brieuc (1) , Guilhem Dezanneau (1) , Marc Hayoun (2) , Hichem Dammak (1)

1 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
2 LSI - Laboratoire des Solides Irradiés - Irradiated Solids Laboratory

GdBaCo2O5+x compounds have demonstrated to be very efficient cathode materials not only in solid oxide fuel cells but also in proton conducting fuel cells. In this last case, the excellent properties could be due to the presence of mixed electron-proton conduction. We study here the diffusion of the proton in this material using molecular dynamics simulations. Two different diffusion mechanisms are observed. The predominant mechanism is the standard proton transfer between two neighbouring oxygen atoms combined with the rotation of H around its first neighbour oxygen atom. The second mechanism consists in the migration of the OH group where both oxygen and hydrogen atoms diffuse together. Strong spatial correlations between successive proton jumps are evidenced. This is likely related to the presence of oxygen vacancies and to the concerted diffusion of hydrogen and oxygen atoms.

Mots clés: PCFC; Proton conductor; Double perovskite; Mixed conductivity; Molecular dynamics

Domaines: Physique [physics]; Matière Condensée [cond-mat]; Science des matériaux [cond-mat.mtrl-sci]

Fabien Brieuc, Guilhem Dezanneau, Marc Hayoun, Hichem Dammak. Proton diffusion mechanisms in the double perovskite cathode material GdBaCo2O5.5 : A molecular dynamics study. Solid State Ionics, 2017, 309, pp.187 - 191. ⟨10.1016/j.ssi.2017.07.017⟩. ⟨hal-01932509⟩