Thermoelectric Properties of the α-As₂Te₃ Crystalline Phase

Abstract

As₂Te₃ exists in two crystallographic configurations: α- and β-As₂Te₃, of which only the latter crystallizes in the same rhombohedral structure-type as Bi₂Te₃. While β-As₂Te₃ shows interesting thermoelectric (TE) properties which can be adjusted through alloying, the transport properties of the monoclinic phase α-As₂Te₃, more thermodynamically stable than the β-phase at room temperature, has not yet been studied thoroughly. We report here on the samples preparation by powder metallurgy, and on the microstructural characterization of polycrystalline α-As₂Te₃. Preliminary results on the electrical and thermal properties measured between 5 K and 523 K are also reported. Transport properties measurements were performed both along and perpendicular to the pressing direction indicating that the transport properties demonstrate some degree of anisotropy. Remarkably, low thermal conductivity values (below 1 W m⁻¹ K⁻¹ above 300 K) were measured suggesting that this compound may be an interesting platform to design novel TE materials with high efficiency.