Single crystals of Rh3+-doped material were grown from aqueous solution, and were studied by means of electron paramagnetic resonance and electron nuclear double resonance after irradiation at liquid-N temperatures. Complexes of the form, [RhCl6]4–, with 2 next-nearest neighbor charge-compensating vacancies were detected. The 2 vacancy-Rh2+ axes were at an angle of 90º to each other, and were perpendicular to the center symmetry axis. After warming the sample, centers with C2v symmetry decayed consecutively into 2 other [RhCl6]4– centers that had been found previously in Rh3+-doped NaCl and AgCl Bridgman crystals, and/or in solution-grown NaCl:Rh3+ crystals, irradiated at room temperature, respectively.

Electron Nuclear Double Resonance of a Nearly Axial Rh2+ Center in Solution-Grown NaCl Crystals. F.Callens, H.Vrielinck, P.Matthys, M.Zdravkova, H.Vercammen, D.Schoemaker: Journal of Applied Physics, 1998, 84[1], 422-7