Trapping of irradiation-induced defects by tin atoms in an Al-0.03 at.% Sn crystal

The backscattering-channeling method was used to investigate the trapping of irradiation-induced defects by Sn atoms in an Al-0.03 at.% Sn crystal. Since Sn atoms were not displaced appreciably from lattice sites by irradiation of the crystal at 35 or 70 K, or by subsequent annealing up to 160 K, it was concluded that mixed dumbbells were not formed by interstitial trapping in that temperature range. Further annealing up to 220 K produced a considerable displacement of Sn atoms from lattice sites. Channeling measurements along the $〈110〉$, $〈100〉$, and $〈111〉$ axes indicated that the displaced Sn atoms were located in tetrahedral and octahedral interstitial sites. These displacements were attributed to multiple vacancy trapping at Sn atoms, because further irradiation at 70 K reduced the apparent displaced fraction of Sn atoms more than did irradiation at 35 K. Annealing at temperatures above 240 K caused a change in the Sn atom positions, indicating an alteration of the configuration of vacancy clusters.