MOLAR VOLUME VARIATION AND IONIC-CONDUCTION IN MOLTEN ERCL3-NACL AND ERCL3-KCL SYSTEMS

Molar conductivities (Lambda) of molten ErCl3-NaCl and ErCl3-KCl systems were evaluated using the data of molar volume, V-m, and conductivity, kappa, which were measured as a function of the mole fraction of ErCl3 and temperature, by dilatometry and a conventional a.c. technique, respectively. The Lambda values of molten ErCl3 were smaller than those of molten YCl3, in which a loose disordered network of edge-sharing octahedral units has been reported to exist. The Lambda values of ErCl3-NaCl and ErCl3-KCl systems increased with decreasing ErCl3 concentration, x, and in the range x > 0.25 the increment in Lambda with x was much smaller than that in the range of x < 0.25. In a series of molten rare earth chlorides, Lambda values have been found to be affected qualitatively by cationic radii and the types of linkage, that is, corner- or edge-sharing of octahedral units.