THE ELECTRICAL CONDUCTIVITY OF SOLUTIONS OF METALS IN THEIR MOLTEN HALIDES. VII. RARE EARTH METAL SYSTEMS. ELECTRON EXCHANGE BETWEEN ADJACENT OXIDATION STATES

The electrical conductivities of solutions of the series La, Pr, and Nd in their molten tribromides are similar to those of the corresponding chloride and iodide systems. The rapid increase in conductivity with metal concentration in the La solutions indicates the occurrence of considerable electronic conductance; in a solution of 10% La metal, as high as nine times the ionic conductance. The Nd solutions show little if any electronic conductance, while the Pr solutions are again intermediate. Solutions of Gd, Dy, Ho, and Er in their molten trichlorides behave irregalarly both in regard to solubility and electrical conductance. A maximum in conductance near 50 mole% MX/sub 2/ dissolved in MX/sub 3/ was found in NdBr/sub 3/--NdBr/sub 2/ as it had been in Ndl/sub 3/Ndl/sub 2/, and positive deviation from additivity was obtained in and positive deviation together with their absence in the systems NdCl/sub 3/- SrCl/ sub j2/ and Ndl/sub 3/- SrI/sub 2/ support an earlier explanat ion based on electron exchange between adjacent oxidation states (Nd/sup 3+/ - Nd/sup 2+/, Dy/ sup 3+/-Dy/sup 2+/). (auth)