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- Title
Hydrogen dynamics features in BaZrScO(OH): high-temperature H NMR studies.
- Authors
Buzlukov, A.; Arapova, I.; Verkhovskii, S.; Gerashenko, A.; Stepanov, A.; Leonidov, I.; Leonidova, O.; Kozhevnikov, V.
- Abstract
The H nuclear magnetic resonance measurements were carried out to study proton dynamics features in the hydrated scandium-doped barium zirconate, BaZrScO(OH), with x = 0.2 and 0.4 in the temperature range 300-600 K. The obtained data evidence a fast proton motion in both samples, which is characterized by the jump frequency of about 10 s at 450 K. However, the microscopic nature of hydrogen diffusion in these two samples is quite different. For the sample with x = 0.2, hydrogen motion mechanisms are defined by a rapid chemical exchange between Sc-OH-Zr and Zr-OH-Zr positions. The estimated value of activation energy for hydrogen diffusion of about 0.5 eV is determined by the energy barrier produced by Sc ion. The increase of Sc concentration to x = 0.4 leads to the drastic changes of sample properties. Experimental results allow to assume the formation of nanoscaled Sc-rich domains and the decomposition of hydrogen sublattice with formation of two proton subsystems: the protons in Zr-OH-Zr coordinations and those concentrated in Sc-OH-Sc environments. The proton motion in both these subsystems is rather fast, but the chemical exchange between them is highly suppressed. Hydrogen motion inside Sc-rich environments has most likely localized nature. Our estimates yield the energy values of about 0.25 and 0.55 eV for hydrogen motion in 'free lattice' and in Sc-rich clusters, respectively. The Sc-rich domains can retain hydrogen up to 600 K.
- Subjects
MAGNETIC resonance; SCANDIUM compounds; BARIUM zirconate; DIFFUSION; PROTONS
- Publication
Journal of Solid State Electrochemistry, 2016, Vol 20, Issue 3, p609
- ISSN
1432-8488
- Publication type
Article
- DOI
10.1007/s10008-015-3086-2