Polarization in LaF3

Abstract

We report the results of measurements of the low‐frequency dielectric behavior and of persistent polarization in single‐crystal LaF₃. This ionic conductor exhibits unusually large polarization effects. The measurements distinguish at least two components of polarization. One component, with a time constant of the order of milliseconds, is linear in the applied voltage; the long‐term polarization is proportional to its square. The phenomena are evidently associated with surface effects, but they cannot be described by the accepted space‐charge theory of ionic conductors. They appear, however, to be qualitatively consistent with an extension of the notion of ionic surface states introduced by Frenkel.