Electrical Conductivities of Alkaline Earth Sulfides

Abstract

In order to find a sulfide solid electrolyte with high ionic conductivity, the electrical conductivities of alkaline earth sulfides and CaS doped with a rare earth sulfide or a titanium group sulfide were measured by the ac bridge-complex impedance plot method at 1073–1673 K. From the dependence of the conductivity on sulfur partial pressure, the ionic conduction of these sulfides was evaluated. MgS, CaS and SrS showed ionic conduction at low sulfur partial pressure, but their conductivities were too low as a solid electrolyte. BaS and CaS doped with a rare earth sulfide exhibited high conductivity due to the electronic conduction. CaS doped with a titanium group sulfide showed ionic conduction except at low sulfur pressure. CaS doped with TiS2 showed high ionic conductivity. Among these sulfides CaS doped with TiS2 was found to be the most suitable solid electrolyte for determination of sulfur in liquid iron.