Low thermal conductivity and good thermoelectric performance in mercury chalcogenides

Thermoelectric (TE) property refers to converting thermal energy into electrical energy via Seebeck effect. Theoretically, the presence of a low thermal conductivity and a high thermoelectric power factor in a same material promises a good thermoelectric performance. In this paper, we investigate the thermal transport and thermoelectric properties of crystalline mercury chalcogenides (HgX, X = O, S, Se, Te) based on first-principles calculations combined with Boltzmann transport equation and electron-phonon interaction (EPI). Remarkably, the calculated lattice thermal conductivity kappa(L) of the semiconducting mercury chalcogenides (alpha-HgO and alpha-HgS) are fairly low (kappa(L) similar to 0.60 W/mK at 300 K, which is about 38% of the value for the typical thermoelectric material PbTe), while the corresponding power factors S-2 sigma for alpha-HgS are relatively high, which, as a result, leads to a good thermoelectric performance in alpha-HgS, with the thermoelectric figure of merit ZT even exceeding 1.28. However, the highest ZT of alpha-HgO is only 0.58 due to the relatively low S-2 sigma. For comparison, the lattice thermal conductivity kappa(L) of the semimetallic mercury chalcogenides (beta-HgS, beta-HgSe, and beta-HgTe) are much higher than that of PbTe, limiting the applications in thermoelectricity. These results indicate that semiconducting mercury chalcogenides may be potential candidates for the design of thermoelectric generators.

Automated summary

Thermoelectric property involves the conversion of thermal energy into electrical energy via Seebeck effect. This study focused on the thermal transport and thermoelectric properties of crystalline mercury chalcogenides, revealing that semiconducting mercury chalcogenides exhibit good thermoelectric performance due to low thermal conductivity and high power factors. In contrast, the lattice thermal conductivity of semimetallic mercury chalcogenides is higher, limiting their applications in thermoelectricity.