TRIAC Progress Report - KEK

consideration is highly required for quantitative discussion. From the experimental point
of view, however, it would be interesting to extend the measurement to the more
Li-poor composition of LiIn recently confirmed to have the β-phase in the same
composition [3-45] as investigated for β-LiGa in the present work.
Using the method mentioned above, tracer diffusion coefficient of lithium ions in
the perovskite-type structured lithium ion conductors (La2/3-xLi3xTiO3; LLTO) have also
been measured in the experiment of RNB-K07 (Spokesperson: S. Takai (Tottori Univ.),
Collaboration: Tottori Univ. (1), KEK (8), JAEA (4)). The diffusion coefficients were
consistent with those obtained by neutron radiography method [3-46] measured above
200°C (Fig. 3-32). The tendency that lower lithium concentration with higher A-site
vacancy possesses higher diffusion coefficients was confirmed around room
temperature. Additional experiments for the sample of x=0.166, which is A-site stuffed
composition, has been performed and the data analysis is in progress. In the experiments,
a quenched sample with higher crystal symmetry was also studied and would help
clarify the contribution of disordering of the vacancy.
s -1
D / cm 2
10 -5
10 -6
10 -7
Temperature, t /
500 300 200 100 50
o C
10
1 2 3
-8
T -1 / kK -1
Fig. 3-32. Arrhenius plots of diffusion coefficients of LLTO measured by radiography () and the
present 8 Li () methods. Red, blue and black symbols are for x = 0.066, 0.116 and 0.166,
respectively.
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