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This work presents a study on the electrochemical behavior of actinides (An ϭ Am and Pu͒ and lanthanides (Ln ϭ La and Nd͒ onto solid aluminum cathodes in a molten LiCl-KCl eutectic at 733 K. Cyclic voltammetry of these elements onto Al working electrode is carried out to estimate the reduction potentials of An and Ln and to predict the efficiency of an An/Ln separation by electrolysis. Results show that the reduction of Am 3ϩ , Pu 3ϩ , La 3ϩ , and Nd 3ϩ ions leads to the formation of An-Al or Ln-Al surface alloys. Moreover, the difference in reduction potentials between An and Ln elements was found to be larger than on the classical molten cadmium or bismuth electrodes. Pu/Nd and Am/Nd electroseparations were carried out using Al foam as cathode and a plutonium rod as anode. Efficient and faradaic reduction of actinides was achieved at a cathodic potential preventing Nd coreduction. After electrolysis, a compact and adherent deposit covered the cathode surface, and scanning electron microscopy, energy-dispersive X-ray analysis of the deposit indicated the existence of Al 4 -Pu or mixed Am-Pu-Al alloys. Analysis of the dissolved Al cathodes, after electrolytic separation of Am from Nd, showed that 536 mg of An ͑94% of the total Am present in the initial salt phase͒ had been deposited compared to less than 3 mg Nd. This work represents a breakthrough in the selective partitioning of An by electrorefining methods.

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307of CoC12(g) at the gas-solid interface being determined by the equilibrium between Co304(s) and the partial pressures of C12(g) and 02(g) in the corrosive gas mixture. At lower partial pressures of oxygen, the corrosion rate is controlled by mixed diffusion of C12(g) and CoCl,(g) through the gas boundary layer.The activities of CaO and Al2O3 in lime-alumina melts were studied by Knudsen cell-mass spectrometry at 2060 K. Emf of solid state cells, with CaF2 as the electrolyte, was measured from 923 to 1223 K to obtain the free energies of formation of the interoxide compounds. The results are critically evaluated in the light of data reported in the literature on phase equilibria, activities in melts, and stabilities of compounds. A coherent set of data is presented, including the previously unknown free energy of formation of CaO. 6AI20, and the temperature dependence of activities in the liquid phase.

A device is described to facilitate direct comparative measurements of vapor pressures with multiple effusion cells attached to a mass spectrometer, particularly for the reproducibility of mechanical repositioning of the cells and the ionization conditions of the molecular beam in the ion source. Measurements show that with this device this method can be applied satisfactorily to the determination of thermodynamic activities in high-temperature systems.

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