Effect of the defects on Li diffusion in irradiated B4C

Understanding lithium behavior in boron carbide (B 4 C) is essential for assessing its performance under neutron irradiation in nuclear environments. In this study, samples implanted with 170-keV Li were annealed and/or irradiated with 10-MeV Au ions. The Li profiles were measured by TOF-SIMS. The defect structure was studied by DBS using a slow positron beam. The disorder level was obtained by Raman spectroscopy. We show that Li diffusion in B 4 C is mainly controlled by trapping and detrapping processes, with an apparent activation energy of ∼ 0.93 eV for Li detrapping. At high defect level (10 16 Li cm −2 or with Au co-irradiation), larger defects or Li clusters are formed, promoting strong Li trapping and reducing the diffusion. However, at 10 14 Li cm −2 , the trapping is reduced at the damage peak, inducing shorter Li residence times and apparent local enhanced diffusion.