By means of perturbed γγ angular correlation experiments, using the radioactive dopants 77Br, 111Ag and 111In, the behavior of the group-I elements Li, Cu, Ag and Au was investigated. Group-I elements were shown to form nearest-neighbor and next-nearest neighbor donor-acceptor pairs. The simultaneous occurrence of cation vacancies indicated the transition, of group-I elements, from substitutional to interstitial lattice sites. In the case of nearest-neighbor pairs, the electric-field gradients measured in the perturbed angular correlation experiments were compared with those obtained theoretically using density-functional theory calculations.

Defect Interactions of Group-I Elements in Cubic II-VI Compounds. V.Ostheimer, S.Lany, J.Hamann, H.Wolf, T.Wichert, Isolde: Physical Review B, 2003, 68[23], 235206 (9pp)