Abstract
The fluorite structured mixed metal fluorides Rb1−xBixF1+2x (0.5≤x≥0.75) are exceptionally good F− ion conductors, a property which is clearly related to the mixed nature of the cation sub-lattice. Extended X-ray absorption fine structure (EXAFS) has been used to study the local structure of the two types of cation in Rb1−xBixF1+2x as a function of x. The results reveal marked differences for the local environments of Rb+ and Bi3+. Considerable short-range order develops as x deviates from 0.5, and this can be correlated with the relative conductivities of these materials. Molecular dynamics (MD) has been used to yield complementary information on structural properties. Simulations were performed for a series of temperatures between 80 K and 750 K. Excellent agreement between EXAFS and MD is obtained. A non-collinear interstitialcy mechanism is proposed for anion diffusion, which is seen to be the basis for more complex concerted processes.
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J. M. Reau, S. F. Matar and J-L. Soubeyroux, Solid State Ionics 9&10 (1983) 563.
S. F. Matar, PhD thesis, University of Bordeaux, Bordeaux (1983).
W. M. C. I. Jordan, PhD thesis, University of London, London (1989).
J. W. Pierce and Y. H-P. Hong, in “Proceedings of the 10th rare earth research conference carefree”, edited by C. J. Kevane and T. Moeller, Vol. A2 (NTIS, Springfield, Va, 1973) p. 527.
E. A. Stern in “Chem. anal”. 92 (X-ray Absorpt.) (New York, 1988) p. 3.
P. A. Lee, P. H. Citrin, P. Eisenberger and B. M. Kincaid, Rev. Mod. Phys. 53 (1981) 769.
T. M. Hayes and J. B. Boyce, Solid State Physics 37 (1984) 173.
M. J. Gillan, Physica 131B (1985) 157.
E. Pantos and D. Firth, in “EXAFS and near edge structure”, edited by A. Bianconi, L. Incoccia and S. Stipcich (Springer-Verlag, Berlin, 1983) p. 110.
C. R. A. Catlow, A. V. Chadwick, G. N. Greaves and L. M. Moroney, Nature 312 (1984) 601.
J. R. Walker in “Computer simulation of solids”, edited by C. R. A. Catlow and W. C. Mackrodt (Springer-Verlag, Berlin, 1982) p. 65.
C. R. A. Catlow, M. J. Norgett and T. A. Ross, J. Phys. C10 (1977) 1627.
M. J. Gillan and M. Dixon, ibid. C13 (1980) 1901.
C. R. A. Catlow, Solid State Ionics 8 (1983) 89.
M. J. Gillan, in “Solid state ionics '83”, edited by H. Kloitz, B. Sapoval and D. Ravaire (Amsterdam, North Holland, 1983) p. 755.
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Cox, P.A., Catlow, C.R.A. & Chadwick, A.V. EXAFS and molecular modelling studies of Rb1−xBixF1+2x . JOURNAL OF MATERIALS SCIENCE 29, 2725–2733 (1994). https://doi.org/10.1007/BF00356824
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DOI: https://doi.org/10.1007/BF00356824