NEW THERMOELECTRIC MATERIALS

The substitution of Te for Se was explored in the well-studied α-As₂Te₃ in order to study the changes in the electronic band structure and thermoelectric properties. The electrical resistivity and thermopower gradually increase with Se due to the progressive increase in the band gap. Se substitution further lowers the lattice contribution to thermal conductivity reaching 0.35 W m⁻¹K⁻¹ above 300 K in α- As₂Te_1.5Se_1.5. Unfortunately Se substitution does not enable achieving higher thermoelectric performances in comparison to substitutions of Sn and Bi for As. Several compositions in the Cu-As-Te glassy system were prepared by melt quenching followed by SPS. The electrical transport properties of Cu_xAs_55-xTe₄₅, Cu₁₅As_85-yTe_y and Cu₂₀As_80-yTe_y compositions were probed, displaying high electrical resistivity (>10^-2 Ωm) and high thermopower (>500 µVK^-1), as typically observed in chalcogenide glasses. Although the thermal conductivities measured are low (<0.3 Wm^-1K^-1), ZT values remain below 0.1, mainly due to the too high electrical resistivity.