Synthesis, crystal structure and mono-dimensional thallium ion conduction of TlFe(0.22)Al(0.78)As(2)O(7)

A new solid solution TlFe0.22Al0.78As2O7 has been synthesized by a solid-state reaction. The structure of the title compound has been determined from a single-crystal X-ray diffraction and refined to final values of the reliability factors: R(F2) ¼ 0.030 and wR(F2) ¼ 0.081 for 1343 independent reflections with I42s(I). It crystallizes in the triclinic space group P-1, with a ¼ 6.296(2)A ˚ , b ¼ 6.397(2)A ˚ , c ¼ 8.242(2)A ˚ , a ¼ 96.74(2)1, b ¼ 103.78(2)1, g ¼ 102.99(3)1, V ¼ 309.0(2)A ˚ 3 and Z ¼ 2. The structure can be described as a threedimensional framework containing (Fe/Al)O6 octahedra connected through As2O7 groups. The metallic units and diarsenate groups share oxygen corners to form a three-dimensional framework with interconnected tunnels parallel to the a, b and c directions, where Tl+ cations are located. The ionic conductivity measurements are performed on pellets of the polycrystalline powder. At 683 K, The conductivity value is 5.23106 S cm1 and the ionic jump activation energy is 0.656 eV. The bond valence analysis reveals that the ionic conductivity is ensured by Tl+ along the [001] direction.