Enhancing Thermoelectric Properties of (Cu₂Te)_1--(BiCuTeO) Composites by Optimizing Carrier Concentration

Because of the high carrier concentration, copper telluride (Cu₂Te) has a relatively low Seebeck coefficient and high thermal conductivity, which are not good for its thermoelectric performance. To simultaneously optimize carrier concentration, lower thermal conductivity and improve the stability, BiCuTeO, an oxygen containing compound with lower carrier concentration, is in situ formed in Cu₂Te by a method of combining self-propagating high-temperature synthesis (SHS) with spark plasma sintering (SPS). With the incorporation of BiCuTeO, the carrier concentration decreased from 8.1 × 10²⁰ to 3.8 × 10²⁰ cm^-3, bringing the increase of power factor from ~1.91 to ~2.97 μW cm^-1 K^-2 at normal temperature. At the same time, thermal conductivity reduced from 2.61 to 1.48 W m^-1 K^-1 at 623 K. Consequently, (Cu₂Te)_0.95-(BiCuTeO)_0.05 composite sample reached a relatively high ZT value of 0.13 at 723 K, which is 41% higher than that of Cu₂Te.