Nuclear Instruments and Methods in Physics Research. Section B, Beam interactions with materials and atoms vol:106 issue:1-4 pages:23-27
The lattice site occupation of oversized atoms, implanted in Ni and Fe at 60, 180 and 293 K has been studied extensively using the or-emission channeling technique. Low dose (<10(12) at/cm(2)) implantations of Fr-221 and Ra-221 guarantee a study of the lattice site of Fr, At, Ra and Rn without overlap of multiple collision cascades in the direct environment of the implanted atom. Monte Carlo channeling simulations are compared with the experimental channeling patterns. Two possible lattice sites can be identified: the substitutional site and a random site. A substantial substitutional fraction is observed, even for room temperature implantations.