Conductivity and 7Li diffusion in molten lithium borates were studied. The direct-current conductivity of a melt with high viscosity exhibited an exponential temperature dependence for various compositions, x = Li2O/(Li2O+B2O3). The activation energy for direct-current conductivity was equal to 1.47eV for x = 0.2, to 1.10eV for x = 0.25, to 1.23eV for x = 0.34 and to 0.77eV for x = 0.5. The activation energy for 7Li diffusion in the melt, as evaluated using nuclear magnetic resonance, was equal to 0.37eV for x = 0.07 and to 0.69eV for x = 0.67. The activation energy for Li diffusion was much smaller than that for conduction in B-rich specimens. They were comparable in more Li-rich specimens. It was suggested that small mobile Li+ cations dominated conduction in Li-rich specimens whereas anionic groups in boric oxides, which were large in size and slow to move in the melt, were responsible for the activation energy for conduction in B-rich specimens.

Electric Field Application to Molten Lithium Borates. T.Katsumata, N.Suzuki, M.Shibasaki, T.Matsuo: Proceedings of the SPIE, 1999, 3792, 242-9