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- Karlsson, Maths, 1978, et al.
(författare)
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Quasielastic neutron scattering of hydrated BaZr0.90A0.10O2.95 (A = Y and Sc)
- 2009
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 180:1, s. 22-28
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Tidskriftsartikel (refereegranskat)abstract
- 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 ~ 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. © 2008 Elsevier B.V. All rights reserved.
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| 2. |
- Karlsson, Maths, 1978, et al.
(författare)
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Vibrational Properties of Protons in Hydrated BaInxZr1-xO3-x/2
- 2005
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 72, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the local proton dynamics in the proton conducting hydrated perovskite system BaInxZr1-xO3-x/2 (x=0.25-0.75) using infrared spectroscopy and first-principles calculations. We show that oxygen vacancies and dopant atoms in the vicinity of the proton tilt the proton toward a neighboring oxygen creating strongly hydrogen-bonded configurations. This is manifested as a strong redshift of the O-H stretch band in the infrared absorption spectrum. We also find considerable fluctuations of the nearest and next-nearest oxygen-proton distances with time, resulting in additional spectral broadening. By comparing the frequencies of computed O-H stretch modes we can relate specific local configurations to different parts of the broad O-H stretch band. Even though hydrogen-bonded configurations favor proton transfer they hinder the long-range migration by decreasing the reorientational rate. Thus, in order to optimize the proton mobility it is important to avoid extreme configurations caused by either oxygen vacancies or dopant atoms in the perovskite structure.
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