Synthesis and properties of rare earth containing Bi2Te3 based thermoelectric alloys

Rare earth (RE) (Ce, Sm and Er) containing bismuth telluride nano-powders were synthesized in ethanol at 150 °C for 24 h by solvothermal processes using rare earth oxides, bismuth chloride, tellurium powders as the precursors. Bulk thermoelectric (TE) materials were prepared by hot-pressing the powders in a vacuum of about 0.1 Pa with a pressure of 65 MPa at 300 °C for 30 min. The rare earth contents in the Bi2Te3 based compounds were about 3-4 at.%. They occupy the Bi-position in the Bi2Te3 lattice and act as n-type dopant in Bi2Te3 based semiconductors. Texture with the Bi2Te3 (0 0 1) planes parallel to the disk base-face formed during hot-pressing of the solvothermally synthesized nano-powder. A maximal figure of merit ZT ≈ 0.22 has been obtained for a sample of Ce-Bi2Te3 at about 450 K.