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Article Dans Une Revue Solid State Ionics Année : 2006

Microstructural and electrical characterisation of melt grown high temperature protonic conductors

Marie-Hélène Berger
F. Dynys
  • Fonction : Auteur

Résumé

High temperature protonic conductors of SrCe1−xYxO3−δ and Sr3Ca1+xNb2−xO9−δ were fabricated by directional solidification to produce model microstructures. Elongated cells exhibited left angle bracket100right-pointing angle bracket direction parallel to the growth axis; low degree of disorientation was observed between the cells. In the simple perovskite SrCe1−xYxO3−δ aluminum contamination caused the formation of intergranular second phase. Nuclear microprobe revealed that the second phase was enriched with hydrogen. Impedance spectroscopy revealed that the protons at grain boundaries have a lower mobility than within the cells. The cation distribution was not uniform in the complex perovskite. Inverse gradients in Ca2+ and Nb5+ were observed from the core to the shell of the cells. The Nb5+ substitution decreased from x = 0.12 at the core to 0.07 at the shell. Higher Nb5+/Ca2+ ratio at the shell decreased the protonic conductivity. Nanodomain were observed in both perovskite compositions; they differentiate by a 90° rotation of the direction of oxygen cage tilting. In the complex perovskite, stoichiometric domains with an ordered distribution of Nb5+ and Ca2+ were surrounded by nonstoichiometric domains with a random distribution of these cations. Further work and analyses are required to understand the mechanism of proton transfer within domains and across domain interfaces.

Dates et versions

hal-00133467 , version 1 (26-02-2007)

Identifiants

Citer

Marie-Hélène Berger, A. Sayir, F. Dynys, P. Berger. Microstructural and electrical characterisation of melt grown high temperature protonic conductors. Solid State Ionics, 2006, 177, pp.2339-2345. ⟨10.1016/j.ssi.2006.04.033⟩. ⟨hal-00133467⟩
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