Ionic conductivity and activation volumes in the lead halides PbCl2, PbBr2, and PbI2

Abstract

The effect of hydrostatic pressure on the ionic conductivities of PbCl2, PbBr2, and PbI2 has been investigated. Activation volumes for vacancy motion in PbCl2 and PbBr2 are found to be 4.7 and 4.4 cm3/mole, respectively. Defect-formation volumes are found to be large in PbCl2 and PbBr2, and consistent with the dominance of Schottky defects in those materials. The activation volumes for PbI2 are all found to be small and consistent with the dominance of Frenkel defects in both the low-pressure layered hexagonal phase and in the high-pressure phase. Transition temperatures and pressures are given for the high-pressure phase transition in PbI2 and are found to agree with values reported elsewhere. © 1980 The American Physical Society.