Xe bubble formation in Xe-implanted Fe as observed by the channelling method

In order to investigate the initial stage of Xe bubble formation in alpha-F e, the lattice location of Xe atoms has been studied by the channelling met hod for the Fe crystals in;implanted with Xe ions at 150 keV at room temper ature up to doses 10(14), 4 x 10(14), 10(15) and 10(16) Xe/cm(2). Most of t he Xe atoms are located at substitutional (S) and random (R) sites. At low implantation doses small portion of them are located at tetrahedral (T) sit es and the sites slightly displaced from a lattice point by about 0.085 nm in the [111] direction (D site). With increasing implantation dose the frac tions of S-, D- and T-site occupancies decrease, whereas that of the R-site occupancy increases. These results suggest that at the initial stage of im plantation Xe-vacancy (V) complexes, i.e., XeV, XeV4 and larger ones, are f ormed and they act as nucleation centres for the subsequent growth to Xe bu bbles.