It was noted that this material crystallized in a quasi-linear CsNiCl3-type structure that contained linear chains of [CdBr6]4− octahedra, separated by parallel chains of Cs+. Trivalent rare-earth ions replaced the divalent Cd ions. The requirement of charge compensation led to the creation of a number of rare-earth centers. The most prominent of these was the symmetrical pair center RE3+-(Cd vacancy)–RE3+. Madelung calculations for various centers established a ranking system for their probable existence. Experimental optical spectroscopic and sub-mm electron spin resonance data were provided for the most likely centers. The symmetrical pair center was of special interest for cooperative phenomena involving RE3+ ions. These included direct ion–ion interactions and interactions with, or via, electronic excitations of the host lattice.

The Rare-Earth Centers in CsCdBr3. J.Heber, R.Demirbilek, M.Altwein, B.Z.Malkin, V.F.Tarasov: Journal of Alloys and Compounds, 2002, 341[1-2], 12-8