Electrical properties of the hexagonal modification of lithium iodide

It has been found that LiI films evaporated on SiO2 substrates at pressures lower than 10-3 Torr exhibit hexagonal type structure (for film thickness at least up to 50 μm) as confirmed by the X-ray analysis data. The electrical conductivity of these films was studied as a function of temperature and thickness. An irreversible structural transition from hexagonal to the ordinary cubic phase wast detected at about 85 C, accompanied by a hump on the conductivity curve. The activation energy of the hexagonal phase was equal to ∼0.5 eV. The character of the frequency dependence of the ac conductivity indicates that the main contribution comes from ionic transport in polycrystalline grains. 9 refs.; 4 tabs