Tracer diffusion experiments on LISICON and its solid solutions by means of neutron radiography

Lithium ion diffusion coefficient measurements were carried out on LISICON (Li3.5Zn0.25GeO4) and on a zinc-rich analogue (ZRA; Li3Zn0.5GeO4) using neutron radiography (NR). Smearing 6LiNO3-saturated solution on a surface of a rectangle-shaped sample consisting of 7Li and subsequent annealing enabled the relatively low temperature diffusion experiment down to 300 °C. The measured isotope concentration profiles agreed well with the diffusion model from the surface into the semi-infinite media, and the diffusion coefficients can be obtained for both LISICON and ZRA in the temperature range between 300 and 500 °C. The diffusion coefficient of LISICON is essentially larger than that of ZRA, while similar a Haven ratio was found. This indicated that the larger conductivity in LISICON was mainly caused by the higher lithium ion mobility and not by the difference of diffusion path.