Dielectric relaxation losses in lead chloride and lead bromide: Localized dipoles

Abstract

A further analysis of previous reported measurements of dielectric relaxation losses in lead chloride and lead bromide crystals shows that the dipoles may occupy several energetically different positions, giving rise to localization of the dipoles and anomalous behaviour of the susceptibility. This energy difference is determined. Inspection of the crystal structure shows that the anion vacancy, being the mobile part of the dipole (which is an associate like (MePb·VX)x or (OX·VX)x where X = Cl, Br), may jump indeed between halide ion sites with different coordination number.

A comparison between the dipole concentration as calculated from the observed losses and the associate concentration as estimated from ionic conductivity experiments leads to the conclusion that local field corrections in the calculations are important.