Synthesis, characterisation and thermoelectric properties of the oxytelluride Bi2O2Te

•Bi2O2Te crystallises in the anti-ThCr2Si2 structure type.•Bi2O2Te is an n-type semiconductor, with a band gap of 0.23 eV.•The thermal conductivity of Bi2O2Te approaches values found for amorphous solids.•The thermoelectric figure of merit of undoped Bi2O2Te reaches 0.13 at 573 K.

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.

Graphical abstractBi2O2Te, which crystallises in the anti-ThCr2Si2 structure type, is an n-type semiconductor with a remarkably low thermal conductivity. Figure optionsDownload full-size imageDownload as PowerPoint slide