How thermoelectric properties of p-type Tl-filled skutterudites are improved

Abstract

The high-temperature thermoelectric properties of p-type Tl-filled skutterudites TlxFe1Co3Sb12 (x = 0, 0.2, 0.4, 0.6, and 0.8) were examined. While samples with x ≤ 0.4 were single-phase Tl-filled skutterudite, samples with x = 0.6 and 0.8 were composed of two phases: TlxFe1Co3Sb12 (x ≈ 0.4) as the matrix phase and a Tl-Fe-Sb ternary alloy. The thermal conductivity (κ) was reduced effectively by Tl addition, but the secondary phase increased κ slightly. The maximum value of the dimensionless figure of merit ZT (=S2T/ρ/κ, where T is the absolute temperature) was 0.36 at 723 K for Tl0.2Fe1Co3Sb12

Enhanced thermoelectric properties of Ga and In Co-added CoSb3-based skutterudites with optimized chemical composition and microstructure

“…As shown in TABLE II, the x =0. 35 21,33 By fitting the calculated lattice parameter to the experimental value, we obtained x ≈ 0.09, which was in good agreement with x = 0.09 of the actual composition determined by the Rietveld analysis. This result implies that the assumptions utilized for the Rietveld analysis are valid; in other words, in the case of Ga and In co-coped CoSb 3 , In easier occupies the void sites as compared to Ga, which occupies not only the void sites, but also the Sb sites at a ratio of 2:1.…”

“…Furthermore, the maximum values of the absolute S for these samples shifted to higher temperatures with increasing x, mainly due to the onset of a bipolar conduction caused by the increased electron concentration. 35 On the other hand, when x reaches 0.45, the absolute values of S and ρ start increasing. As a result, the samples with x = 0.35 and 0.45 exhibited similar characteristics in terms of S 2 ρ −1 , corresponding to high values in the temperature range of 300700 K (above 4 mW m -1 K -2 ) with a relatively flat temperature dependence (the origin of such a high power factor will be discussed later).…”

“…In particular, CoSb 3 -based filled skutterudites are considered promising TE materials. Alkali metals, 11,12 alkaline earth elements, [13][14][15] lanthanides, [16][17][18][19][20][21][22][23][24] electronegative elements, 25,26 and group 13 elements [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] are known as good candidates for filler elements. Among group 13 elements, indium (In), as a co-dopant in multiple filled skutterudites, show excellent TE properties of maximum zT values of 1.2-1.4, in which co-dopants such as Barium, Cerium and Ytterbium easily react with air and thus the special process is required to apply for mass production.…”

High-temperature thermoelectric properties of p-type skutterudites Ba0.15Yb x Co3FeSb12 and Yb y Co3FeSb9As3

“…Thus far, n-type skutterudites have been widely investigated, resulting in relatively high ZT values from single, double, and triple atom filling [5,6,9]. Since both p-and n-type materials are essential for thermoelectric modules, enhancing the thermoelectric properties of p-type skutterudites are the current focus [10][11][12][13][14][15][16][17][18][19][20][21][22]. The small hole effective mass for p-type skutterudites, as compared to the much larger electron effective mass in n-type compounds, makes optimization of the thermoelectric properties of ptype skutterudite compounds much more challenging [5,6,23].…”

Thermoelectric Properties of In<i>_x</i>FeCo₃Sb₁₂ Consisting Mainly of In-Filled <i>p</i>-Type Skutterudites

“…Leszczynski et 4 Sb 12 (y > 1/3), these impurity phases lead to the reduction of Seebeck coefcient. 24,25) To avoid the heavy precipitation of impurity phases, we prepared, in the present study, the sample at In x FeCo 3 Sb 12 (x = 0.3, 0.5, 0.7, and 0.9), and their TE properties were examined from room temperature to 773 K to investigate the effects of the In-lling and the Fe substitution on the TE properties.…”