Physical Properties of Molten Li2CO3-Na2CO3 (52:48 mol%) and Li2CO3-K2CO3 (62:38 mol%) Containing Additives

Physical properties such as density, surface tension, and electrical conductivity of molten Li2CO3-Na2CO3 (52:48 mol%) or Li2CO3-K2CO3 (62:38 mol%) containing additive ions (K+, Rb+, Cs+, F-, Cl-, SO42-, CrO42-, MoO42-, or WO42-) by 5 mol% were investigated to elucidate and predict additive ions' effects. Each ionic molar volume of an additive anion was estimated from density data of pure alkali molten salts containing the anion. Results showed that the molar volume of molten mixtures can be estimated using the constituent ionic molar volumes. Results show that the reciprocal molar volume of the molten mixtures has a linear relation with the surface tension, except for the mixture containing large single-charged ions of Cs+, or Cl-, which decreased the surface tension effectively. The conductivity of the molten mixture decreased with the increase in molar volume. The relation can be used to estimate conductivity of mixtures. The equivalent conductivity of ternary alkali carbonate added with K+, Rb+, and Cs+ can be predicted using the containing cationic radii and the equivalent conductivities of the component pure carbonates. (C) 2013 The Electrochemical Society. All rights reserved.