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.