Negative Temperature Coefficients of Electrical Conductance in Molten Salts

Abstract

The electrical conductivities of molten CuCl, HgCl2, HgBr2, SnCl2, InI3, ZnI2, ZnCl2, TlCl, TlBr, TlI, and HgI2 were measured to temperatures as high as 1200°C. Maxima in conductivity as the temperature was increased were found in the first six salts. Since molten BiCl3, BiBr3, BiI3, CdI2, GaI3, pure water, and aqueous solutions containing weak and strong electrolytes also exhibit a conductivity maximum at elevated temperatures, it is concluded that this behavior is general to all fluids at sufficiently high temperature and sufficiently reduced density. These maxima in fused salts are attributed to increasing covalency or ionic association as the density decreases.