The lattice sites of 8Li atoms which had been implanted into Zn-rich monocrystals, at temperatures of 100 to 600K, were investigated by means of emission channelling measurements. It was found that implantation at temperatures below 210K resulted in the occupation of mainly tetrahedral interstitial sites. Upon increasing the temperature to 260K, the fraction on substitutional lattice sites increased. It was proposed that the onset of interstitial Li diffusion, and capture by Zn vacancies, was responsible for the lattice site change. This implied a Li migration energy of between 0.47 and 0.59eV. At temperatures of between 260 and 360K, the occupation of tetrahedral interstitial sites again became favourable. This was attributed to the interaction of LiZn with other defects. At temperatures above 360K, these complexes could dissociate while Li on substitutional sites was still stable. At temperatures above 450K, the dissociation of substitutional Li led to its diffusion to extended defect complexes such as precipitates or dislocations. An activation energy of 1.33eV was estimated for this process.

S.G.Jahn, U.Wahl, M.Restle, H.Quintel, H.Hofsäss, M.Wienecke, I.Trojahn, Isolde: Materials Science Forum, 1995, 196-201, 315-20

Figure 31

Diffusivity of Pt in ZnSe