Self-diffusion of lithium in molten LiBeF3 and Li2BeF4
- 1 January 1979
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 75, 1277-1283
- https://doi.org/10.1039/f29797501277
Abstract
The self-diffusion coefficients of lithium in molten Li2BeF4 and LiBeF3 have been measured by the capillary reservoir technique using 6Li as a tracer. The concentration profiles of 6Li in a capillary were measured by an ion micro-mass-analyser and the self-diffusion coefficients D were calculated. The results can be described using the Arrhenius equation, D= 9.27 × 10–7 exp [(–32.5 ± 8.4)× 103/RT] standard error: ± 1.1 × 10–9(Li2BeF4) and D= 1.12 × 10–6 exp [(–38.9 ± 12.5)× 103/RT] standard error: ± 4.3 × 10–10(LiBeF3), where D is expressed in m2 s–1, R in J mol–1 K–1 and T in K. The activation energy for diffusion of lithium is much smaller than that of fluorine and slightly larger than that for electrical conductivity. These results suggest that the movement of fluorine does not involve electric current transfer and the mobility of lithium ions is much larger than that of the fluoroberyllate ion. The self-diffusion coefficients of lithium in molten LiBeF3 are smaller than those in molten Li2BeF4. However, the activation energies are similar in molten Li2BeF4 and LiBeF3.Keywords
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