Details
| Original language | English |
|---|---|
| Pages (from-to) | 7117-7129 |
| Number of pages | 13 |
| Journal | Journal of Physical Chemistry C |
| Volume | 118 |
| Issue number | 13 |
| Publication status | Published - 3 Apr 2014 |
Abstract
Ba1-xLaxF2+x covering the whole range of compositions was synthesized by high-energy ball milling of mixtures of BaF 2 and LaF3 at ambient temperature. The compounds obtained in this way crystallize in the cubic fluorite structure in the range from 0 ≤ x-0.775 which extends the range for the fluorite-type Ba1-xLa xF2+x covered up to now (0 ≤ x ≤ 0.55) considerably. By employing 19F NMR spectroscopy and X-ray (total) scattering, indications for a continuous change from the fluorite (BaF2) to the tysonite structure (LaF3) were found. The mechanosynthesized samples showed slightly higher fluoride ion conductivities for the samples with x ≤ 0.40 and clearly smaller conductivities in the case of the samples with x ≥ 0.85 than reported for their monocrystalline counterparts. Two conductivity maxima at x ≈ 0.40 and x ≈ 0.85 and a conductivity minimum at x ≈ 0.75 were observed for the mechanosynthesized Ba1-xLaxF 2+x. For the samples with 0.10 ≤ x ≤ 0.50, exhibiting a dc conductivity in the order of 10-5 S/cm at 400 K, all fluoride ions seem to be highly mobile at temperatures beyond 453 K. The decrease of the ionic conductivity observed for Ba1-xLaxF2+x with increasing x in the range from x ≈ 0.50 to x ≈ 0.75 is accompanied by a change of the diffusion behavior and a decrease of the ratio of highly mobile to nonmobile or slow fluoride ions.
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Energy(all)
- General Energy
- Chemistry(all)
- Physical and Theoretical Chemistry
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Journal of Physical Chemistry C, Vol. 118, No. 13, 03.04.2014, p. 7117-7129.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Mechanosynthesis of the fast fluoride ion conductor Ba1-xLa xF2+ x
T2 - from the fluorite to the tysonite structure
AU - Düvel, A.
AU - Bednarcik, J.
AU - Šepelák, V.
AU - Heitjans, P.
PY - 2014/4/3
Y1 - 2014/4/3
N2 - Ba1-xLaxF2+x covering the whole range of compositions was synthesized by high-energy ball milling of mixtures of BaF 2 and LaF3 at ambient temperature. The compounds obtained in this way crystallize in the cubic fluorite structure in the range from 0 ≤ x-0.775 which extends the range for the fluorite-type Ba1-xLa xF2+x covered up to now (0 ≤ x ≤ 0.55) considerably. By employing 19F NMR spectroscopy and X-ray (total) scattering, indications for a continuous change from the fluorite (BaF2) to the tysonite structure (LaF3) were found. The mechanosynthesized samples showed slightly higher fluoride ion conductivities for the samples with x ≤ 0.40 and clearly smaller conductivities in the case of the samples with x ≥ 0.85 than reported for their monocrystalline counterparts. Two conductivity maxima at x ≈ 0.40 and x ≈ 0.85 and a conductivity minimum at x ≈ 0.75 were observed for the mechanosynthesized Ba1-xLaxF 2+x. For the samples with 0.10 ≤ x ≤ 0.50, exhibiting a dc conductivity in the order of 10-5 S/cm at 400 K, all fluoride ions seem to be highly mobile at temperatures beyond 453 K. The decrease of the ionic conductivity observed for Ba1-xLaxF2+x with increasing x in the range from x ≈ 0.50 to x ≈ 0.75 is accompanied by a change of the diffusion behavior and a decrease of the ratio of highly mobile to nonmobile or slow fluoride ions.
AB - Ba1-xLaxF2+x covering the whole range of compositions was synthesized by high-energy ball milling of mixtures of BaF 2 and LaF3 at ambient temperature. The compounds obtained in this way crystallize in the cubic fluorite structure in the range from 0 ≤ x-0.775 which extends the range for the fluorite-type Ba1-xLa xF2+x covered up to now (0 ≤ x ≤ 0.55) considerably. By employing 19F NMR spectroscopy and X-ray (total) scattering, indications for a continuous change from the fluorite (BaF2) to the tysonite structure (LaF3) were found. The mechanosynthesized samples showed slightly higher fluoride ion conductivities for the samples with x ≤ 0.40 and clearly smaller conductivities in the case of the samples with x ≥ 0.85 than reported for their monocrystalline counterparts. Two conductivity maxima at x ≈ 0.40 and x ≈ 0.85 and a conductivity minimum at x ≈ 0.75 were observed for the mechanosynthesized Ba1-xLaxF 2+x. For the samples with 0.10 ≤ x ≤ 0.50, exhibiting a dc conductivity in the order of 10-5 S/cm at 400 K, all fluoride ions seem to be highly mobile at temperatures beyond 453 K. The decrease of the ionic conductivity observed for Ba1-xLaxF2+x with increasing x in the range from x ≈ 0.50 to x ≈ 0.75 is accompanied by a change of the diffusion behavior and a decrease of the ratio of highly mobile to nonmobile or slow fluoride ions.
UR - http://www.scopus.com/inward/record.url?scp=84898066764&partnerID=8YFLogxK
U2 - 10.1021/jp410018t
DO - 10.1021/jp410018t
M3 - Article
AN - SCOPUS:84898066764
VL - 118
SP - 7117
EP - 7129
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 13
ER -