Abstract
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.
Highlights
Introduction by Optimizing Carrier ConcentrationWith the capability of direct conversion from thermal energy to electrical energy through the movement of internal phonons and charge carriers, thermoelectric (TE) materials are widely researched and used in cogeneration, electronic refrigeration and thermal sensors [1–7]
As x = 0, the Cu2 Te is composed of Cu2 Te (PDF#06-0649), Cu2−δ Te (PDF#10-0421) and Cu0.664 Te0.336 (PDF#37-1027), similar to the previous study [33]
The standard Powder Diffraction File (PDF) card is calculated according to the literature data [41]
Summary
With regard to the thermoelectric properties of BiCuXO, most previous studies focus on BiCuSeO due to the high Seebeck coefficient and low thermal conductivity, but low conductivity [38]. Cu2 Te with BiCuTeO to lower the thermal conductivity and improve the Seebeck coefficient of Cu2 Te by optimizing the carrier concentration. We synthesized (Cu2 Te)1−x -(BiCuTeO)x composites by self-propagating hightemperature synthesis (SHS) and spark plasma sintering (SPS) process to optimize carrier concentration (n) and decrease the total thermal conductivity. The PF was raised from ~1.91 to ~2.97 μW cm−1 K−2 at normal temperature, and the (Cu2 Te)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 pristine Cu2 Te
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