5La 3Ta 2O 12: A combined quasi-elastic neutron scattering and molecular dynamics study]]>

摘要

AbstractIn this work lithium self-diffusion in the model lithium garnet oxide Li5La3Ta2O12was investigated by combining quasi-elastic neutron scattering experiments and molecular dynamics simulation. TheQ-dependence of the quasi-elastic broadening measured experimentally and of the mean relaxation rate of lithium calculated by molecular dynamics simulations were both well described by the Singwi-Sj?lander diffusion model. This model describes lithium nuclei that undergo diffusion via a jump-type mechanism consisting of a distribution of jumps with a mean square jump distance and residence time. The extracted mean jump length is consistent with a jump between tetrahedral (24d) to octahedral (48gand 96h) sites within theIa3ˉdsymmetry structure and the residence time of Li at these sites obeys an Arrhenius relation from ~ps timescales at 1100K to the ~ns range at 400K. This result supports a lithium diffusion mechanism in which jumps are more frequent (smaller residence time) and shorter at higher temperature. The self-diffusivities of Li from both experiment and calculation were in good agreement, but deviations from those previously measured using nuclear magnet