Internal cation mobility in molten LiCl–NdCl 3 system

Abstract

Internal mobilities of Li + and Nd 3+ cations have been investigated in binary unsymmetrical molten LiCl–NdCl 3 system by countercurrent electromigration method (so-called Klemm method). The results have been presented as isotherms of cation internal mobilities versus equivalent fraction of NdCl 3 for 1023, 1073 and 1123 K and have been compared with corresponding relationships for NaCl–NdCl 3 and KCl–NdCl 3 systems. It has been found that internal mobility of Nd 3+ ions (as well as Li +) increases with decreasing concentration of NdCl 3, contrary to KCl–NdCl 3 and NaCl–NdCl 3 systems for which Nd 3+ internal mobility decreases or is nearly constant, respectively. The tendency that smaller alkali metal cation enhances internal mobility of trivalent ion ( b Ln) has been described with a simple equation: b Ln = b Ln 0 + a ( 1 − y LnC l 3 ) 2 , where b Ln 0 is the internal mobility of Ln 3+ in molten LnCl 3, y LnC l 3 the equivalent fraction of LnCl 3 and a parameter is the difference between internal mobility of Ln 3+ cation in molten LnCl 3 and internal mobility of this cation in infinitely diluted solution of LnCl 3 in alkali metal chloride.