The conductivity of well-annealed crystals of the pure chloride, and of samples which were doped with Sr or S, was measured over a wide range of temperatures. The conductivity data were analyzed by using a multi-parameter non-linear least-squares technique. The defect model which was used allowed for the possible existence of Frenkel defects on both the cation and anion sub-lattices and for the association of cation vacancies with divalent cations and of anion vacancies with divalent anions. A consistent set of defect parameters was obtained.

P.W.M.Jacobs, M.L.Vernon: Radiation Effects and Defects in Solids, 1995, 137[1-4], 247-50