Current‐Induced Segregation in Ionic Melts

The criteria for the electrochemically driven demixing of cations in ternary molten salts and silicates are analyzed for two cases of selective ion blocking electrodes. Mathematical expressions are derived for an anion flux case and a cation flux case which relate the concentration profiles and current densities at steady state to the differences of the electrical and chemical potentials applied at the melt surfaces. The analysis can be used to evaluate component demixing if three independent transport coefficients are known as a function of composition. Conversely, demixing experiments are proposed for use in determining such parameters as the inter diffusion coefficient and transference numbers of each ion for the composition range of segregation.