Diffusion of 6Li in Ta and W

The objective of this work was the study of ⁶Li diffusion in the Ta and W refractory metals. The samples were prepared by ion implantation of 380 keV ⁶Li⁺ ions into W and Ta thin foils (up to the fluence of 10¹⁶ ions/cm²) and annealed up to the temperature 1940 °C. The depth profiles of ⁶Li were determined using the Thermal Neutron Depth Profiling (TNDP) technique. The results showed that diffusion of ⁶Li in both W and Ta foils is very complex and cannot be described by simple Fick's laws. Trapping centers (in the subsurface layers of both W and Ta metals) were supposed in a trial to explain the ⁶Li diffusion behaviour. However, the ⁶Li depth profiles were only partly explained. Other aspects are necessary to take into account for more proper quantification; such as spatially dependent diffusion coefficients, etc.