It was found that the conductivity versus temperature curves of pure or doped material exhibited 4 regions (table 191). A region, IA, occurred in doped and non-doped samples and was tentatively attributed to protonic conduction due the presence of OH. Region IB was attributed to extrinsic conduction. Region II was suggested to involve conduction via intrinsic vacancies. At high temperatures, a new region (III) appeared. Its presence was attributed to O contamination and/or to the motion of relatively immobile interstitials. The conductivity of the pure material was higher than that of the doped material. It was suggested that this was because some of the K formed complexes with known or unknown impurities which were then unable to release the charge carriers.

M.D.Shareefuddin, K.V.S.Rao, U.V.S.Rao, K.N.Reddy, M.N.Chary: Crystal Research and Technology, 1990, 25[1], K20-3

Table 191

Activation Energies for Ionic Conduction in KYF4-SmF3