Polycrystalline samples of material which was doped with 0.5 to 2%NaF were investigated at temperatures of between 370 and 770K. It was found that, for NaF contents of up to 1%, exchange between the 2 different anion sub-lattices increased and was reflected by an increase in conductivity. At NaF contents above 1%, fluoride ions interchanged easily among the various anion sub-lattices. Overall, the material exhibited 4 different regions with increasing temperature (table 190). In region I, conduction occurred via extrinsic vacancies. In region 2, conduction involved intrinsic vacancies. In region 3, conduction involved intrinsic interstitials. In region 4, the behavior was tentatively attributed to the loss of F.

M.Shareefuddin, U.V.S.Rao, K.N.Reddy, M.N.Chary: Crystal Research and Technology, 1990, 25[11], K278-82

Table 190

Activation Energies for Ionic Conduction in the KYF4-NaF System