Ionic Conduction in LaF3Thin Films

Ionic thermoconductivity and electrical conductance as a function of temperature have been determined experimentally over the temperature range 219-519 °K for thin evaporated films of La${\mathrm{F}}_3$. From these measurements the activation energy for ${\mathrm{F}}^{-}$ diffusion through the film is determined to be 0.40 ± 0.08 eV below 500 °K except in the vicinity of the Debye temperature (360 °K). Above 500 °K this activation energy increases to 0.80 ± 0.10 eV. The mechanism of charge transfer is discussed in light of the crystal structure and existing magnetic data for La${\mathrm{F}}_3$.