DIFFUSION OF LI-6 ISOTOPES IN LITHIUM ALUMINATE CERAMICS USING NEUTRON DEPTH PROFILING

Lithium Ceramics offer tremendous potential as a source for the production of tritium (H-3) for fusion power reactors. Their successful application will depend to a great extent upon the diffusion properties of the Li-6 within the matrix. Consequently knowledge od Li-6 concentration gradients in the ceramic matrices is an important requirement in the continued development of the technology. In this investigation, the neutron depth profile (NDP) technique has been applied to the study of concentration profiles of Li-6 in lithium aluminate ceramics, doped with 1.8%, 50% and 95% Li-6 isotopic concentrations. Specimen for analysis were prepared at Battelle (PNL) as pellet discs. Samples for diffusion studies were arranged as diffusion couples in the following manner: 1.8% Li-6 discs/85% Li-6 powder. Experiments were performed at the Texas A&M Nuclear Science Center Reactor Building, utilizing 1 MW equivalent thermal neutron fluxes 3 x 10(11) n/m2s. The depth probed by the technique is approximately 15 mum. Diffusion coefficients are in the range of 2.1 x 10(-12) to 7.0 x 10(-11) m2 s-1 for 1.8% Li-6-doped ceramics annealed at 1200 and 1400-degrees-C, for 4 to 48-h anneal times.