An Fe+-type center, with axial <001> symmetry, was studied by means of electron nuclear double resonance in the microwave X and Q bands. The Fe+(I) center was produced only after X- or γ-irradiation, at 80K, of Fe2+-doped crystals that had been grown in a Cl2 atmosphere. It had a 3d7 4FΓ8 ground state, with S = 3/2. As shown by an analysis of the electron nuclear double resonance data and electron paramagnetic resonance superhyperfine structure, the Fe+ ion was situated at the center of a tetragonally compressed cube of 8 nearest Cl- ions. The simplest model, for the Fe+(I) center, that was compatible with the magnetic resonance results consisted of an interstitial Fe+ ion with 2 substitutional monovalent cations. The latter were probably K+ ions, and were located in 2 opposite nearest-neighbor Sr2+ sites along the tetragonal axis of the center.

Magnetic Resonance Study of the Fe+ (I) Center in SrCl2 Single Crystals. H.Vrielinck, F.Callens, P.Matthys, S.V.Nistor, D.Ghica, D.Schoemaker: Physical Review B, 2001, 64[2], 024405 (9pp)