Synthesis, characterisation and thermoelectric properties of the oxytelluride Bi₂O₂Te

Bi₂O₂Te was synthesised from a stoichiometric mixture of Bi, Bi₂O₃ and Te by a solid state reaction. Analysis of powder X-ray diffraction data indicates that this material crystallises in the anti-ThCr₂Si₂ structure type (space group I4/mmm), with lattice parameters a=3.98025(4) and c=12.70391(16) Å. The electrical and thermal transport properties of Bi₂O₂Te were investigated as a function of temperature over the temperature range 300≤T (K)≤;665. These measurements indicate that Bi₂O₂Te is an n-type semiconductor, with a band gap of 0.23 eV. The thermal conductivity of Bi₂O₂Te is remarkably low for a crystalline material, with a value of only 0.91 W m^-1 K^-1 at room temperature.