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X-Ray Absorption Spectroscopy and Computer Modelling Study of Nanocrystalline Binary Alkaline Earth Fluorides
DOI:
10.1088/1757-899X/80/1/012005
Authors:
A . V.
Chadwick
(University of Kent at Canterbury)
,
A.
Duvel
(Leibniz University of Hannover)
,
P.
Heitjans
(Leibniz University of Hannover)
,
D. M.
Pickup
(University of Kent)
,
S.
Ramos
(University of Kent)
,
D. C.
Sayle
(University of Kent)
,
T. X. T.
Sayle
(University of Kent)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Iop Conference Series: Materials Science And Engineering
, VOL 80
State:
Published (Approved)
Published:
April 2015
Diamond Proposal Number(s):
8912

Abstract: Nanocrystalline samples of Ba1-xCaxF2 prepared by high-energy milling show an unusually high F- ion conductivity, which exhibit a maximum in the magnitude and a minimum in the activation energy at x = 0.5. Here, we report an X-ray absorption spectroscopy (XAS) at the Ca and Sr K edges and the Ba L3 edge and a molecular dynamics (MD) simulation study of the pure and mixed fluorides. The XAS measurements on the pure binary fluorides, CaF2, SrF2 and BaF2 show that high-energy ball-milling produces very little amorphous material, in contrast to the results for ball milled oxides. XAS measurements of Ba1-xCaxF2 reveal that for 0 < x <1 there is considerable disorder in the local environments of the cations which is highest for x = 0.5. Hence the maximum in the conductivity corresponds to the composition with the maximum level of local disorder. The MD calculations also show a highly disordered structure consistent with the XAS results and similarly showing maximum disorder at x = 0.5.
Subject Areas:
Materials,
Chemistry,
Physics
Instruments:
B18-Core EXAFS