Neutron diffraction and electrical conductivity studies of Li2UI6 ionic conductor

The room and high temperature structures of Li2UI6 have been determined using the neutron powder diffraction. It has been shown that at 300 K, the compound crystallizes in trigonal unit cell with a = b = 7.3927(8), c = 13.826(2) Angstrom with space group P-31c. Above the phase transition occuring at 775 K, the structure transforms into monoclinic C 2/m space group with unit cell constants: a = 7.733(5), b = 13.234(7), c = 7.645(4) Angstrom, beta = 110.59(3) deg. The measurement of electrical conductivity as a function of temperature has been performed. Based on the crystallographic data, a discussion of the shape of observed conductivity curve has been carried out.