Quasielastic neutron scattering of hydrated BaZr(0.90)A(0.10)O(2.95) (A = Y and Sc)

• Proton motions in hydrated proton conducting perovskites BaZr(0.90)A(0.10)O(2.95) (A = Y and Sc) have been investigated using quasielastic neutron scattering. The results reveal a localized motion on the ps time scale and with an activation energy of similar to 10-30 meV, in both materials. The temperature dependence of the total mean square displacement of the protons shows an onset of this motion at a temperature of about 300 K. The low activation energy, much lower than the activation energy for the macroscopic proton conductivity, suggests that this motion is not the rate-limiting process for the long-range proton diffusion, i.e. it is not linked to the two materials significantly different proton conductivities. In fact, a comparison of the QENS results with density functional theory calculations indicates that for both materials the observed motion may be ascribed to intra-octahedral proton transfers occurring close to a dopant atom. (C) 2008 Elsevier B.V. All rights reserved.

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Proton conducting

Perovskite

Quasielastic neutron scattering

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