Thermoelectric properties of Sn- and Pb-doped Tl9BiTe6 and Tl9SbTe6

Abstract

A variety of substitutions in Tl9BiTe6 and Tl9SbTe6 with Sn and Pb, amounting to 14 different samples, were performed by melting the stoichiometric amounts of elements at 923 K, followed by slow cooling. The pulverized powders were sintered using the hot-pressing technique. All samples were of single phase according to the powder X-ray diffraction patterns. Thermoelectric property measurements were performed to investigate the effects of Sn- and Pb-doping on the electrical conductivity, Seebeck coefficient, and thermal conductivity. Increasing the concentration of the dopants caused increases in electrical and thermal conductivity, while decreasing the Seebeck coefficient. Tl9Bi0.90Pb0.10Te6 and Tl9Bi0.85Pb0.15Te6 exhibited the highest power factor. The changes in lattice thermal conductivity were minor and did not follow a clear trend. Competitive ZT values were obtained for Tl9Bi0.95Sn0.05Te6, Tl9Bi0.95Pb0.05Te6, Tl9Sb0.97Sn0.03Te6, and Tl9Sb0.95Pb0.05Te6, namely 0.95, 0.94, 0.83, and 0.71 around 500 K, respectively. Higher dopant concentrations led to lower ZT values.

Thermoelectric properties of hot-pressed Tl9LnTe6 (Ln=La, Ce, Pr, Nd, Sm, Gd, Tb) and Tl10−xLaxTe6 (0.90⩽x⩽1.05)

“…Moreover, the j L curves are very flat, which is characteristic of compounds with the thermal conductivity approaching the phonon-glass limit. The same j L behavior was also found in the Sn-and Pb-doped Tl 9 BiTe 6 and Tl 9 SbTe 6 [27]. As also can be observed from Fig.…”

Metavalent Bonding-Mediated Dual 6s2 Lone Pair Expression Leads to Intrinsic Lattice Shearing in n-Type TlBiSe2

“…Tl-chalcogenide-based thermoelectric materials generally show p-type character and rarely exhibit n-type conducting behavior. However, both p- and n-type semiconductors of the same material class is required for thermoelectric device fabrication due to compatibility issues. − To the best of our knowledge, the maximum n-type zT achieved to date among Tl-based chalcogenides is ∼0.15 at 760 K in TlBiTe 2 . Thus, TlBiSe 2 and TlBiSeS with zT ≈ 0.6 and 0.8, respectively, at 715 K are indeed valuable additions to the family of Tl-chalcogenide-based thermoelectric materials with the highest n-type zT reported to date.…”

Phase Equilibria in the Tl4PbTe3-Tl9SmTe6-Tl9BiTe6 Section of the Tl-Pb-Bi-Sm-Te System

“…[7][8][9] Tl 5 Te 3 compound crystallizes in tetragonal structure (Sp.gr.I4/mcm, a = 8.930; c = 12.598 Å), 10,11 and has a number of ternary substitutional analogs of Tl 4 A IV Te 3 and Tl 9 B V Te 6 -type (A IV -Sn, Pb; B V -Sb, Bi), [12][13][14] which also possess a good thermoelectric performance. 15,16 Moreover, authors 17 A new thallium lanthanide tellurides of Tl 9 LnTe 6 -type (Ln-Ce, Nd, Sm, Gd, Tb, Tm) were found to be a new structural analog of Tl 5 Te 3 . 18,19 H. Kleinke and co-workers [20][21][22] confirmed the results of the studies, 18,19 and determined the thermoelectric and magnetic properties for a number Tl 9 LnTe 6 -type compounds.…”