Electrical Conductivity of Molten Li2CO3 – X2CO3 (X: Na, K, Rb, and Cs) and Na2CO3 – Z2CO3 (Z: K, Rb, and Cs)

The electrical conductivities of the molten binary salt mixtures Li 2 CO 3 -X 2 CO 3 (X: Na, K, Rb, and Cs) and Na 2 CO 3 -Z 2 CO 3 (Z: K, Rb, and Cs) were measured using an ac two-probe technique and electrochemical impedance spectroscopy. The electrical conductivities of the eutectic compositions of (Li 0.52 Na 0.48 ) 2 CO 3 and (Li 0.62 K 0.38 ) 2 CO 3 at 923 K were 2.06 and 1.31 S cm -1 , respectively. The conductivity of molten Li 2 CO 3 -X 2 CO 3 (X: Na, K, Rb, and Cs) and Na 2 CO 3 -Z 2 CO 3 (Z: K, Rb, and Cs) decreases with an increase in the ionic radius of X or Z. We have succeeded in correlating the equivalent conductivity of a binary carbonate mixture A, with the composition (x A and x B ), the equivalent conductivities of the pure components A and B (A A and Λ B ), and two parameters (λ A and λ B ) as Λ = x 2 A Λ A + x 2 B Λ B + x A x B (λ A x A + λ B x B ). The pair of interaction parameters (λ A and λ B ) can be estimated for a binary system of molten carbonates using the relationship between the cationic radii and the equivalent conductivities of the pure carbonates.