High‐temperature thermoelectric properties of p‐type skutterudites Yb_x Co₃FeSb₁₂

Abstract

Partially filled polycrystalline p‐type skutterudites of nominal compositions Ybx Co3FeSb12 were synthesized and their thermoelectric properties characterized. The compositions and filling fractions were confirmed with a combination of Rietveld refinement and elemental analysis. The thermoelectric properties were evaluated from 300 K to 810 K. The Seebeck coefficient and resistivity increase while the thermal conductivity decreases with increasing Yb content. A maximum ZT value of 0.85 was obtained at 810 K. This work is part of a continuing effort to enhance the thermoelectric properties of p‐type skutterudites, as this class of materials continues to be of interest for thermoelectrics applications. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhanced thermoelectric performance of optimized Yb-filled and Fe-substituted skutterudite compounds Yb0.6FexCo4− xSb12

“…at 300 K is comparable to that of a similar compound (Yb x Fe y Co 4−y Sb 12 ) reported by Dong et al, 9,20) in which ZT = 0.8 at around 800 K. Therefore, a higher ZT in Yb 0.6 Fe 0.5 Co 3.5 Sb 12 can be achieved in the high-temperature range.…”

“…The highest ZT (0.11) was achieved in Yb 0.6 Fe 0.5 Co 3.5 Sb 12 at 300 K. This value is even higher than those of double Baand Yb-filled Fe-substituted compounds (ZT = 0.05 at 300 K and ZT = 0.6 at 800 K). 34) Moreover, the ZT of Yb 0.6 Fe 0.5 -Co 3.5 Sb 12 at 300 K is comparable to that of a similar compound (Yb x Fe y Co 4−y Sb 12 ) reported by Dong et al, 9,20) in which ZT = 0.8 at around 800 K. Therefore, a higher ZT in Yb 0.6 Fe 0.5 Co 3.5 Sb 12 can be achieved in the high-temperature range.…”

“…6) It has been well proved that filling the Sb-icosahedron voids in CoSb 3 with heavy Yb atoms can notably decrease the thermal conductivity. [7][8][9][10][11][12][13] Previous research findings suggest that the appropriate Yb doping ratio should be approximately 0.2 because a higher Yb doping ratio increases the electric carrier concentration, which would lead to a reduction in Seebeck coefficient and thus a low figure of merit. 14,15) On the other hand, a higher Yb doping ratio contributes to the decrease in thermal conductivity.…”

“…Fe is considered a hole doping element for Co-site substitution because it has one less 3d electron than Co while keeping a similar atomic radius to Co. [16][17][18] Various studies about the thermoelectric properties of Yb-filled or= and Fe-substituted CoSb 3 skutterudite compounds have been carried out. 9,[19][20][21][22][23][24][25][26] However, in most of them, the Fe substitution ratio was fixed and the effects of different rareearth fillers on the TE properties were focused on. For example, the crystal structure and TE properties of Yb x Co 2.5 Fe 1.5 Sb 12 have been reported by Dong et al 20) Kim et al synthesized various Ti x Co 3 Fe 1 Sb 12 (0 ≤ x ≤ 0.8) compounds and studied the effects of Ti filling ratio on the TE properties.…”