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

The neutron-irradiation effects on the electrical resistivities of bet a-(LiAl)-Li-6 and beta-(LiAl)-Li-7 with 48-54 at. % Li at room tempera ture are presented. A remarkable decrease of the electrical resistivit y is observed in the neutron-irradiated beta-(LiAl)-Li-6 with around 5 0 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 vac ancy 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 break up 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 resistivit y. A carrier-scattering model based on the defect structure of beta-Li Al explains consistently the electrical resistivity of beta-LiAl befor e 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 th at defect concentrations estimated in the present work are reasonable. We also find that the Li out diffusion is obstructed by the breakup o f the V-Li-Li-Al complex due to neutron irradiation.