Reactivity, stability and thermoelectric properties of n-Bi2Te3 doped with different copper amounts

The effect of incorporating copper into bismuth selenido telluride matrice via a mechanical alloying process was studied. Different amounts were incorporated, from 0.02% to 2 wt%. Transport properties measurement were carried out from room temperature to 473 K. The results indicate for small amounts of copper a decrease of carrier concentration which can be linked to the reaction of copper with tellurium and/or selenium to form a second phase. For higher copper quantities, carrier concentration rises to a maximum and suddenly decreases with the increased formation of Cu2−xTe phase. Stability of the materials was studied via diffusion tests, these demonstrate that copper clearly migrates inside bismuth selenido telluride matrix and forms the Cu2−x(Se, Te) phase. Once formed this phase does show any sign of reactivity with the matrix resulting in stable transport properties of the material.