Toward Online Nanoscale Diffusion Measurements Using Radioactive ⁸Li Tracer

Abstract

We have examined the feasibility of a new online nanoscale diffusion measurement method using a radioactive 8Li tracer by computer simulations. We have found that the detection limit of the lithium diffusion coefficient can be improved to a low value of 1×10-12 cm2/s by detecting α particles emitted at a small angle relative to a sample surface that is irradiated with a low-energy 8Li beam of about 8 keV.

In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of 8Li

“…In the present case, however, the inherent energy distribution of the a particles is continuous and broad [7]. Although the correspondence between the emitted position and measured energy of the charged particles is not as simple as above-mentioned, it was shown that the tracer diffusion coefficient could be obtained from the time-dependent yields of a particles emitted by diffusing 8 Li with the help of the simulation [8][9][10]. Fig.…”

“…deviation of the values of ''Ratios'' from the constant value of ''1'', were observed by a shallow implantation depth even at the lower temperature than observed by a deep implantation depth (LVSO-523K). The solid line results from the simulation with a diffusion coefficient best reproducing the experimental spectra[10].…”

“…It was shown by a simulation to be accessible to the diffusion over nanometer scale by the diffusion coefficients in the range of 10 À12 cm 2 /s (i.e. the diffusion length of 8 Li in a unit of lifetime is about 22 nm if D = 1 Â 10 À12 cm 2 /s) [10].…”

“…The schematic layout of the new method for the diffusion measurement in nanometer scale (nanometer-scale sensitive method) [10] is shown in Fig. 2.…”

“…The energy range was chosen for best sensitivity by following the discussions in Ref. [10]. As a preliminary result, the lithium diffusion coefficient of 9.2 Â 10 À12 cm 2 /s in thin LVSO foil at 373 K was obtained, by comparing the normalized time spectrum to those from the simulations as described in detail in Ref.…”