The layered metal Ti2PTe2

Crystals of Ti2PTe2 have been synthesised by chemical vapour transport. Ti2PTe2 crystallises, isostructural to the mineral tetradymite (Bi2STe2), in the space group R3¯m with unit-cell parameters a=3.6387(2) Å and c=28.486(2) Å for the hexagonal setting. In the structure, layers of isolated phosphide and telluride anions form an ordered close sphere-packing with titanium cations filling two-thirds of the octahedral voids. From XANES fluorescence, the presence of Ti4+ is clearly established. In accordance with the ionic formula (Ti4+)2(P3−)(Te2−)2(e−) metallic conductivity (ρ=40 μΩ cm at 300 K) and nearly temperature-independent paramagnetism are found. The electronic band structure shows bands of titanium states crossing the Fermi level in directions corresponding to the ab-plane and a band gap along the c-axis.