Thermoelectric Performance of Sn and Bi Double-Doped Permingeatite

Abstract

In this study, mechanical alloying was performed to synthesize permingeatite Cu3Sb1-x-ySnxBiySe4 (0.02 ≤ x ≤ 0.06 and 0.02 ≤ y ≤ 0.04) doped with Sn and Bi. Hot pressing was subsequently conducted to achieve dense sintered bodies. When the Bi content was constant, the carrier concentration increased with the Sn content, but the mobility decreased owing to the increased carrier concentration. In contrast, when the Sn content was constant, the carrier concentration and mobility were not significantly affected by the Bi content. Higher electrical conductivity was observed in specimens with a higher Sn content or lower Bi content; consequently, Cu3Sb0.92Sn0.06Bi0.02Se4 exhibited the highest electrical conductivity. The Seebeck coefficient increased with temperature, and it is inferred that the permingeatite doped with Sn/Bi does not undergo an intrinsic transition until 623 K. In contrast to the electrical conductivity, a higher Seebeck coefficient was obtained in the specimens with a lower Sn content or higher Bi content; consequently, Cu3Sb0.94Sn0.02Bi0.04Se4 exhibited the highest Seebeck coefficient. Cu3Sb0.92Sn0.06Bi0.02Se4 exhibited the maximum power factor, depending on the electrical conductivity and Seebeck coefficient. The electronic thermal conductivity was not significantly affected by temperature, but the lattice thermal conductivity decreased as the temperature increased. However, the thermal conductivity decreased with increasing temperature. Sn doping effectively reduced the lattice thermal conductivity, whereas Bi doping effectively reduced the electronic thermal conductivity; consequently, Cu3Sb0.94Sn0.02Bi0.04Se4 exhibited the lowest thermal conductivity. Finally, the highest dimensionless figure-of-merit of 0.75 was achieved at 623 K by Cu3Sb0.92Sn0.06Bi0.02Se4.

2D Self-Assembly of Large-Sized Inorganic Nanosheets Leading to Enhanced Power Factors in Earth-Abundant Cu3SbSe4-Based Flexible Hybrid Films

“…Many studies investigate Cu 3 SbSe 4 for thermoelectrics due to its low thermal conductivity and high Seebeck coefficient, − whereas its thermoelectric conversion efficiency is restricted by its relatively low PF and electrical conductivity resulting from its low carrier concentration and low carrier mobility. To overcome this limitation, many investigations have been made to optimize its carrier concentration by doping at Cu sites with elements such as Zn and Ag and substitution of Sb by elements like Pb, Sn, , and Bi. ,, Other strategies include Sn and Zr or Hf codoping, Sn and Bi double doping, and Sn and La codoping . However, doping of impurity atoms may also result in dislocations and the formation of the secondary-phase precipitates, and these dislocations and precipitates inevitably serve as scattering centers for carriers and diminish the carrier mobility and PF.…”

“…To overcome this limitation, many investigations have been made to optimize its carrier concentration by doping at Cu sites with elements such as Zn 16 and Ag 17 and substitution of Sb by elements like Pb, 18 Sn, 19,20 and Bi. 17,21,22 Other strategies include Sn and Zr or Hf codoping, 23 Sn and Bi double doping, 24 and Sn and La codoping. 25 However, doping of impurity atoms may also result in dislocations and the formation of the secondary-phase precipitates, and these dislocations and precipitates inevitably serve as scattering centers for carriers and diminish the carrier mobility and PF.…”