It was found that there were 2 distinct regions in the plot of conductivity versus temperature, and these were attributed to intrinsic and extrinsic behaviors. In the intrinsic region, the activation energy was equal to 50% of the formation energy of the defect; plus the mobility enthalpy. In the extrinsic region, the activation energy was simply equal to the motional enthalpy of the F- ion. The activation energy and migrational enthalpy were deduced to be equal to 0.50 and 0.23eV, respectively. The defect formation energy was equal to 0.54eV.

S.Palchoudhuri, G.K.Bichile: Journal of Materials Science Letters, 1987, 6[4], 459-61