The creation of Hg interstitials during ion implantation of mercury cadmium telluride is found to strongly depend on the preferred lattice position of the element implanted. Elements that substitute onto the cation sublattice create significantly more interstitials than elements that sit interstitially or on the anion sublattice. In particular, implants of column II elements Mg and Zn produced much larger interstitial concentrations than implants of column VI elements S and Se. Implants of B, which resides mostly as an interstitial, produced Hg interstitial concentrations intermediate between the column II and column VI ions. Recoils from implant damage also contributed to Hg interstitial formation in heavier mass implants (Zn and Se), but appear to have negligible influence on interstitial generation in implants of lighter ions. ©1997 American Institute of Physics.