| 1. |
- Karlsson, Maths, et al.
(författare)
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Short-range structure of proton-conducting BaM0.10Zr0.90O2.95 (M = Y, In, Sc and Ga) investigated with vibrational spectroscopy
- 2010
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 181:3-4 (Sp. Iss.), s. 126-129
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Tidskriftsartikel (refereegranskat)abstract
- The short-range structures of hydrated and dry samples of the proton-conducting, cubic-structured, acceptor-doped perovskites BaM0.10Zr0.90O2.95 (M=Y, In, Sc and Ga), and, for comparison, BaZrO3, have been investigated using infrared and Raman spectroscopy. The results show that the acceptor-doping leads to local structural distortions of the average cubic structure, most likely related to tilts of (M/Zr)O-6 octahedra, and that the distortions are most pronounced in the Ga-doped material for which we also find additional distortions upon hydration. For the Y-, In- and Sc-doped equivalents the distortions are somewhat weaker and hydration is found to have a reversed, although weak, effect. A comparison of the spectroscopic results to the reported proton diffusivities of the investigated materials would suggest that the much lower proton diffusivity in the Ga-doped material is associated to its stronger structural distortions. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Karlsson, Maths, et al.
(författare)
-
Temperature-Dependent Infrared Spectroscopy of Proton-Conducting Hydrated Perovskite BaInxZr1-xO3-x/2 (x=0.10-0.75)
- 2010
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:13, s. 6177-6181
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the temperature dependence of the O-H stretch band in the infrared absorbance spectra of the proton-conducting hydrated perovskites BaInxZr1-xO3-x/2 (x = 0.10-0.75) over the temperature range -160 to 350 degrees C. Upon increasing temperature from -160 to 30 degrees C, we show that there is a redistribution of protons from nonsymmetrical structural configurations, such as Zr-OH-In and Zr-OH-Zr-vacancy, where the degree of hydrogen bonding between the protons and neighboring oxygens is strong, to symmetrical configurations, such as Zr-OH-Zr and In-OH-In, where hydrogen bonding is weaker. Spectra measured at elevated temperatures, 30-350 degrees C, indicate preferential desorption of protons in sites where the degree of hydrogen bonding is strong, and show that the materials gradually dehydrate with increasing temperature. The dehydration rate is found to be highest in the temperature range 275-325 degrees C. Furthermore, the spectroscopic results indicate that strong hydrogen bonding, caused by dopant-induced short-range structural distortions, is favorable for high proton mobility and that the rate-limiting step in the conduction mechanism is the proton transfer between neighboring oxygens.
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| 3. |
- Karlsson, Maths, 1978, et al.
(författare)
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Using Neutron Spin-Echo To Investigate Proton Dynamics in Proton-Conducting Perovskites
- 2010
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 22:3, s. 740-742
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Tidskriftsartikel (refereegranskat)abstract
- The applicability and potential of neutron spin-echo (NSE) to study proton dynamics in proton-conducting ceramics was studied. The experiment was performed on hydrated BaZr 0,90 Y 0.10 O 2.95 (10Y:BZO), a cubic perovskite with a relatively high proton conductivity. The NSE experiment was performed at the IN15 spectrometer at Institut Laue-Langevin (ILL) in Grenoble, France. The relaxation rate for two Q-values for the temperature 563 K was determined. The first-principles calculations were carried out within the framework of density functional theory (DFT). The calculated diffusion harriers far from Y-dopants are found to he 0.20 and 0.18 eV for the proton transfer and hydroxyl rotation motion, respectively. The binding energy to a Y-dopant is 0.16 eV, and the influence of the Y-dopant on the energetics for the proton is quite extended in space, including both the first and the second coordination shells.
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