Thermoelectric properties of W_1−xNb_xSe_2−yS_y polycrystalline compounds

Abstract

We investigate the thermoelectric properties of bulk polycrystalline samples of WSe2‐based compounds with partial substitutions in the cationic (W) and the anionic (Se) sublattices in the temperature range from 4.2 to 650 K. The substitution of W for Nb leads to a significant increase in the charge carrier concentration, however, deteriorates the charge carrier mobility. In contrast, the substitution of selenium for sulfur increases the charge carrier mobility, the thermal conductivity, and the Seebeck coefficient but conductivity changes non‐monotonical. We show that the addition of sulfur in anionic sublattice affects the grain sizes in the polycrystalline material. Using substitutions in the anionic and cationic sublattices, we find the optimal ratio of the elements for better thermoelectric efficiency. The W0.98Nb0.02Se1.7S0.3 sample showed the best value of the figure of merit ZT = 0.26 (T = 650 K).

Simultaneous Enhancement of the Power Factor and Phonon Blocking in Nb-Doped WSe2

“…This value is ∼13 times larger than that of the pristine WSe 2 . Present results indicate that TE performance of WSe 2 can be improved remarkably through the substitution of Nb for W. Figure compares the maximum ZT max obtained here with that reported in previous work, − which shows that ZT max achieved in the present work is the largest among all of the reported work.…”

“…Yakovleva et al investigated the TE performance (ZT, 0.02) of WSe 2 by Nb doping at a low temperature (<∼300 K). Recently, they also studied the codoping of Nb and S on W and Se sites, respectively, at a temperature range from 77 to 650 K and obtained a ZT of ∼0.26. , However, one notices that all previous studies of WSe 2 were mostly based on the improvement of PF, with κ having substantially large magnitudes. Hence, in order to further elevate TE performance for WSe 2 , it is necessary for one to increase its PF and simultaneously lower its κ sharply.…”

Low Thermal Conductivity and High Thermoelectric Performance of Nb-Doped Quarternary Mixed Crystal Nb0.05W0.95-xMox(Se1–xSx)2

“…Yakovleva et al determined the thermoelectric effectiveness of WSe 2 ( ZT , ∼0.02) by the substitution of Nb at low temperature (300 K). Previously, they have further investigated the codoping of Nb on W and substitution of S on Se and achieved ZT ∼ 0.26. , Recently, Danish et al investigated the thermoelectric efficiency of Nb-doped WSe 2 at high temperatures (from 300 to 850 K) experimentally. Their analysis indicates that the increase in PF is due to a rise in both the density of states (E-DOS) effective mass and the hole carrier concentrations.…”

“…Yakovleva et al determined the thermoelectric effectiveness of WSe 2 (ZT, ∼0.02) by the substitution of Nb at low temperature (300 K). Previously, they have further investigated the codoping of Nb on W and substitution of S on Se and achieved ZT ∼ 0.26 54,55. Recently, Danish et al…”

The Charge Distribution, Seebeck Coefficient, and Carrier Concentration of CuCr0.99Ln0.01S2 (Ln = Dy–Lu)

“…The interlayer gap of AMX 2 can also be opened and filled with guest ions or molecules using a special synthesis approach [ 8 ]. However, cationic substitution is considered to be the most common synthesis route to enhance the functional properties of AMX 2 -based materials [ 9 , 10 , 11 , 12 , 13 , 14 ]. In this context, the quasi-layered copper–chromium dichalcogenide CuCrS 2 and CuCrS 2 -based solid solutions are considered promising functional materials for their the ionic conductivity, specific electrical and magnetic properties, catalytic activity, and light-absorbing properties [ 10 , 13 , 15 , 16 , 17 , 18 , 19 ].…”