Internal Cation Mobilities in the Molten Binary Systems ( Y , La ) Cl3 and ( Y , Dy ) Cl3

Internal cation mobility ratios in the molten systems (Y, La)Cl 3 and (Y, Dy)Cl 3 have been measured at 1073 K by the Klemm method and the electrical conductivities of these systems have been measured by conventional ac techniques. From these studies and the data available on the densities of the pure melts, the internal mobilities, u, have been calculated; u La is greater than u y , while the ionic radius of La 3+ is greater than that of Y 3+ . On the other hand, u Y is slightly greater than u Dy , where the ionic radii are much the same and the mass of Y 3+ is much less than that of Dy 3+ . Internal mobilities of all the cations in both (Y, La)Cl 3 and (Y, Dy)Cl 3 systems decrease with increasing molar volume of the mixtures. The dominant electrically conducting cationic species are conjectured to be the nonassociated rare-earth cations.