An electron paramagnetic resonance study was made of Tl2+ centers in Tl-doped samples of the layered compound. This revealed the presence of neighboring charge-compensating anion vacancies, next to Tl+ impurity ions, in the same lattice layer. In the case of low-temperature X-irradiated samples, the vacancies were thermally activated and moved away from hole-trapped Tl2+ ions at temperatures greater than 120K. This result was in good agreement with the activation energy for vacancy migration (0.35eV) which had previously been estimated from ionic conductivity measurements.

EPR Detection of the Presence and Movement of Anion Vacancies in X-Ray Irradiated PbCl2:Tl+ Crystals. S.V.Nistor, E.Goovaerts, D.Schoemaker: Solid State Communications, 1995, 96[7], 491-5