| 1. |
- Mazzei, Laura, 1988, et al.
(författare)
-
Local Coordination of Protons in In- and Sc-Doped BaZrO3
- 2019
-
Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:43, s. 26065-26072
-
Tidskriftsartikel (refereegranskat)abstract
- Acceptor-doped barium zirconate-based proton conductors are currently receiving considerable attention because of their promise as electrolytes in future electrochemical devices, such as solid oxide fuel cells, but the defect chemistry, especially in regard to the local coordination environment and dynamics of protons in these materials, is unclear. Here, we investigate the local coordination environments and vibrational dynamics of protons in samples of the proton conducting material BaZr1-xMxO3Hx with M = In and Sc, and x = 0.1 and 0.5, using inelastic neutron scattering (INS), infrared (IR), and Raman spectroscopy together with ab initio molecular dynamics (AIMD) simulations. The local coordination of protons is shown to exhibit a rather peculiar dependence on the type and concentration of dopant atoms, as they are found to be similar for BaZr1-xScxO3Hx with x = 0.1 and 0.5 and BaZr1-xInxO3Hx with x = 0.1, whereas for BaZr1-xInxO3Hx with x = 0.5 additional proton sites seem to be present. It is argued that these additional proton sites are characterized by local structural arrangements reminiscent of the fully In-substituted material BaInO3H. The presence of these local structural arrangements points toward different local proton mobilities between BaZr1-xInxO3Hx with x = 0.5 and the other three materials and a higher rate of proton transfer events in brownrnillerite-type local structures.
|
|
| 2. |
- Mazzei, Laura, 1988, et al.
(författare)
-
Local structure and vibrational dynamics in indium-doped barium zirconate
- 2019
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 7:13, s. 7360-7372
-
Tidskriftsartikel (refereegranskat)abstract
- Barium zirconate (BaZrO3), when substituted with trivalent acceptor ions to replace Zr4+, is a proton conducting material of interest for several electrochemical applications. The local coordination environments, and vibrational dynamics, of the protons are known to critically influence the material's proton conducting properties, however, the nature of the static and dynamic structure around the protons and, especially, how it is affected by the dopant atoms for high doping concentrations, remains to be elucidated. Here we report results from X-ray powder diffraction, infrared (IR) spectroscopy, inelastic neutron scattering (INS) and ab initio molecular dynamics (AIMD) simulations on a hydrated sample of BaZrO3 substituted with 50% In3+. The investigation of the momentum-transfer (Q) dependence of the INS spectrum is used to aid the analysis of the spectra and the assignment of the spectral components to fundamental O-H bend and O-H stretch modes and higher-order transitions. The AIMD simulations show that the INS spectrum is constituted of the overlapping spectra of protons in several different local structural environments, whereas the local proton environments for specific protons are found to vary with time as a result of thermally activated vibrations of the perovskite lattice. It is argued that, converse to more weakly doped systems, such as 20% Y-doped BaZrO3, the dopant-proton association effect does not hinder the diffusion of protons due to the presence of percolation paths of dopant atoms throughout the perovskite lattice.
|
|
