Tunable thermoelectric transport properties of Cu_0.008Bi₂Te_2.7Se_0.3 via control of the spark plasma sintering conditions

Polycrystalline bulks of n-type Cu_0.008Bi₂Te_2.7Se_0.3 were prepared to investigate the controllability of its thermoelectric transport properties by using the compaction conditions of spark plasma sintering (SPS). The 00l crystal orientation to the press direction of the SPSed bulks was easily improved by increasing the applied pressure at 500 °C. The thermoelectric figure of merit, ZT values (0.72 − 0.75 at 300 K), of all samples were almost the same, however, both the electronic and the thermal transport properties could be tuned significantly by adjusting the sintering pressure. This result highlights the feasibility of using pressure-induced sintering as a fabrication technology for Bi₂Te₃-based polycrystalline bulks with high mechanical reliability, which is an effective means of optimizing the electrical and the thermal conductivities for maximizing the efficiencies of the thermoelectric cooling and the power generation modules.