Electrical conductivity and thermal behavior of solid electrolytes based on alkali carbonates and sulfates

Abstract

Both thermal stability and electrical conductivity of alkali ion conducting Na 2CO 3 and Na 2SO 4, were improved by adding alkaline earth carbonates and sulfates, respectively, as well as insulating materials like γ-Al 2O 3. The admixing of divalent compounds causes two effects. First a more or less extended solution can exist depending on the radius of the alkaline earth ion and is accompanied by an increase in electrical conductivity. Secondly, a phase mixture with an excess of dopant was observed that shows an enhancement in conductivity and mechanical stability. This phenomenon known as composite effect was observed in the following systems: Na 2CO 3-BaCO 3, Na 2CO 3-SrCO 3, Na 2SO 4-BaSO 4, Na 2SO 4-γ-Al 2O 3.