| 1. |
- Noferini, Daria, 1983, et al.
(författare)
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Proton Dynamics in Hydrated BaZr0.9M0.1O2.95 (M = Y and Sc) Investigated with Neutron Spin-Echo
- 2016
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:26, s. 13963-13969
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Tidskriftsartikel (refereegranskat)abstract
- Hydrated samples of the two proton conducting perovskites BaZr0.9M0.1O2.95 (M = Y and Sc) were investigated using neutron spin echo spectroscopy together with thermal gravimetric measurements, polarized neutron diffraction, and infrared spectroscopy, with the aim to determine how the atomic scale proton dynamics depend on temperature, and type of dopant atom, M. The results show the presence of pronounced localized proton motions for temperatures above ca. 300 K, characterized by relaxation times on the order of picoseconds to nanoseconds and governed by a wide distribution of activation energies due to a heterogeneous distribution of proton sites present, with no strong dependence on the type of dopant atom.
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| 2. |
- Sillrén, Per, 1982, et al.
(författare)
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Liquid 1-propanol studied by neutron scattering, near-infrared, and dielectric spectroscopy
- 2014
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 140:12
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Tidskriftsartikel (refereegranskat)abstract
- Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and dynamics is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight and neutron spin-echo techniques, with a focus on the dynamics at length scales corresponding to the main peak and the pre-peak of the structure factor. At the main peak, the structural relaxation times are probed. These correspond well to mechanical relaxation times calculated from literature data. At the pre-peak, corresponding to length scales related to H-bonded structures, the relaxation times are almost an order of magnitude longer. According to previous work [C. Gainaru, R. Meier, S. Schildmann, C. Lederle, W. Hiller, E. Rössler, and R. Böhmer, Phys. Rev. Lett.105, 258303 (2010)] this time scale difference is connected to the average size of H-bonded clusters. The relation between the relaxation times from neutron scattering and those determined from dielectric spectroscopy is discussed on the basis of broad-band permittivity data of 1-propanol. Moreover, in 1-propanol the dielectric relaxation strength as well as the near-infrared absorbance reveal anomalous behavior below ambient temperature. A corresponding feature could not be found in the polyalcohols propylene glycol and glycerol.
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| 3. |
- Karlsson, Maths, et al.
(författare)
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Dopant Concentration and Short-Range Structure Dependence of Diffusional Proton Dynamics in Hydrated BaInxZr1-xO3-x/2 (x=0.10 and 0.50)
- 2010
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:7, s. 3292-3296
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Tidskriftsartikel (refereegranskat)abstract
- We investigate proton self-dynamics in the acceptor-doped and hydrated proton-conducting perovskite-type oxides BaInxZr1-xO3-x/2 (x = 0.10 and 0.50) on a microscopic length scale for temperatures in the range 470-525 K, using neutron spin-echo spectroscopy. For the highly doped material (x = 0.50), we observe a wide range of translational diffusional rates of the protons in the Structure, oil the nanosecond time scale and with in effective activation energy of about 0.75 eV. The wide distribution of diffusional rates is related to the In-doping, which creates local structural distortions or the average Cubic Structure and thus many structurally different Configurations of the protons, each with slightly different energy barriers for the protonic motion. For the weakly doped material (x = 0.10), which has a more ordered local Structure, the results show proton dynamics oil a Much more well-defined time scale, similar to 60 ps at 500 K, but also Suggest that a significant part of the protons ill the Structure are "immobile" within the experimental neutron spin-echo time window (similar to 5 ps to 1.3 ns). Furthermore, the results indicate that the dopant atoms affect the proton diffusion ill a nonlocalized manner and not as well-localized trapping centers.
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