Electronic Conduction in Bi–BiI3 Melts. A Theoretical Model

Abstract

Experimental electrical conductivity data for the liquid Bi–BiI3 system are analyzed in terms of predominant conduction in the salt-rich region by an electronic ``jumping'' or exchange process between the mono- and tervalent states of bismuth. Calculations of the jump frequency from the conductivity data show the expected dependence on temperature and average distance between exchange sites. Results of the calculations are used to evaluate the average energy barrier height for the exchange process and the enthalpy of symmetrization of the ionic atmospheres about the exchange sites, as required by the Franck-Condon principle. The latter is found to be independent of the average distance between exchange sites.