Thermoelectric Properties of the alpha-As2Te3 Crystalline Phase

As2Te3 exists in two crystallographic configurations: alpha- and beta-As2Te3, of which only the latter crystallizes in the same rhombohedral structure-type as Bi2Te3. While beta-As2Te3 shows interesting thermoelectric (TE) properties which can be adjusted through alloying, the transport properties of the monoclinic phase alpha-As2Te3, more thermodynamically stable than the beta-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 alpha-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.