Miscibility Gaps in Fused Salts

Twelve systems formed with lithium fluoride and alkali halides were studied in order to put into evidence possible demixing phenomena. Liquiddiquid equilibra were found in the seven mixtures containing KBr, KI, RbBr, Rbl, CsCl, CsBr, and Csl; however, the miscibility gaps could be fully detected only for LiF + CsCl, LiF + KBr and LiF + RbBr. The tendency to demix in these systems, formed by typically ionic components, agrees with the reciprocal Coulomb effect rule. On the basis of the solid liquid and liquiddiquid equilibria, the LiF excess potentials were evaluated and compared with those calculated according to current theories.