ELECTRICAL CONDUCTIVITY OF La_0.95Sr_0.05F_2.95 CERAMICS AND CRYSTALS

摘要

Electrical transport in La_0.95 Sr_0.05F_2.95 crystals and hot-pressed, low-porosity, gas tight ceramic was studied by impedance measurements as a function of frequency in the temperature range 293-700 K.Below 500 K, the total conductivity of the ceramic is lower than that of the single crystal because grain boundaries impede ionic transport. Above 500 K ,the conductivity of the ceramic coincides with that of the single crystal to within the experimental accuracy, and the activation energy of conductivity is 0.25±0.02 eV. The conclusion is drawn that, at temperatures above 500 K, fast ionic transport in the ceramic is no longer impeded by grain boundaries.