Electron paramagnetic resonance studies were made of Yb ions in weakly-doped material. Analysis of the electron paramagnetic resonance spectra, and of their angular dependence, showed that the Yb3+ ions replaced Cd2+ ions in D3d-symmetry and formed mainly weakly antiferromagnetically coupled symmetrical pair complexes of the type, Yb3+-VCd-Yb3+. These had an interionic separation of about 5.9Å, and a J exchange coupling value of -0.0016/cm. Some weaker resonance lines were attributed to single ion Yb3+ centers in lower-symmetry perturbed sites.

EPR Identification of Coupled Yb3+ Ion Pairs in Optically Bistable Compound CsCdBr3:Yb. V.Mehta, O.Guillot-Noël, D.Simons, D.Gourier, P.Goldner, F.Pellé: Journal of Alloys and Compounds, 2001, 323-324, 308-11