The direct- and alternating-current conductivities of monocrystalline and glass samples were measured at various temperatures. It was shown that the materials were mixed conductors. In the case of the monocrystals, the electronic and ionic conductivities along

the c-axis were much smaller than those perpendicular to the c-axis. The anisotropy of the electronic conduction was attributed to conduction by the  electron of the BO3 layer which was located on the (001) plane. The anisotropy of the ionic conduction was attributed to the diffusion of Li ions and/or protons between the BO3 layers. The thermal activation energies for electronic conduction were equal to 0.65eV (glass), 1.61eV (parallel to c-axis) and 0.78eV (perpendicular to c-axis). The activation energy for ionic conduction was equal to 0.46eV (perpendicular to c-axis).

T.Matsuo, T.Yagami, T.Katsumata: Journal of Applied Physics, 1993, 74[12], 7264-8