Ionic transport studies were made of fluorite phases which had rare-earth trifluoride contents of 20 to 40mol%. The crystals were prepared by using the Stockbarger technique, and impedance spectroscopy was used to measure the conductivity in a vacuum of about 0.01Pa. It was found that the results for each composition could be described by a Frenkel-type law. The conductivity of Ca0.80Lu0.20F2.20, at temperatures ranging from 540 to 772K, could be described by:

σT (SK/cm) = 4.8 x 105 exp[-1.017(eV)/kT]

The conductivity at 500K was equal to 5.5 x 10-8S/cm.

A.K.Ivanov-Shits, N.I.Sorokin, E.A.Krivandina, A.A.Samokhina, B.P.Sobolev: Elektrokhimiya, 1988, 24[11], 1571-4 (Soviet Electrochemistry, 1988, 24[11], 1458-61)