DEFECT STRUCTURE IN NEUTRON-IRRADIATED BETA-(LIAL)-LI-6 AND BETA-(LIAL)-LI-7 - ELECTRICAL RESISTIVITY AND LI DIFFUSION

摘要

The neutron-irradiation effects on the electrical resistivities of beta-(LiAl)-Li-6 and beta-(LiAl)-Li-7 with 48-54 at. % Li at room temperature are presented. A remarkable decrease of the electrical resistivity is observed in the neutron-irradiated beta-(LiAl)-Li-6 with around 50 at. % Li, but not in the neutron-irradiated beta-(LiAl)-Li-7. It is suggested that the defect complex (V-Li-Li-Al) composed of V-Li (a vacancy at the Li site) and Li-Al (a Li antisite atom at the Al site) is an effective scatterer for carriers in beta-(LiAl)-Li-6, and the breakup of the V-Li-Li-Al complex due to the knock on of neutron transmuted H-3 and He-4 induces the abrupt decrease of the electrical resistivity. A carrier-scattering model based on the defect structure of beta-LiAl explains consistently the electrical resistivity of beta-LiAl before and after neutron irradiation. The Li self-diffusion constant shows a linear relationship for [V-f(Li)] (Li content less than or equal to 51.9 at. %) or [V-Li-Li-Al] (Li content greater than or equal to 51.9 at. %) using a conventional diffusion model. This strongly suggests that defect concentrations estimated in the present work are reasonable. We also find that the Li out diffusion is obstructed by the breakup of the V-Li-Li-Al complex due to neutron irradiation. [References: 54]