Electrical and thermal transport properties of Y bxCo4Sb12 filled skutterudites with ultrahigh carrier concentrations

Abstract

For filled skutterudites, element Yb is one of the most common and important fillers. However, the optimal carrier concentration range in Y bxCo4Sb12 filled skutterudites has not been determined as a result of the low Yb filling fraction limit. In this study, a non-equilibrium fabrication process (MS-SPS process), consisting of a melt-spinning method and a spark plasma sintering technique, has been applied to prepare Y bxCo4Sb12 samples. The Yb filling fraction is successfully extended to 0.35, which provides the possibility to clarify the optimal carrier concentration range for Yb-filled skutterudites. High carrier concentrations, with a maximum of around 1 × 1021 cm−3, were achieved in the MS-SPS Y bxCo4Sb12 samples due to the significantly enhanced Yb filling fractions. The phase compositions, lattice parameters, electrical and thermal transport properties of the MS-SPS Y bxCo4Sb12 samples with high carrier concentrations were systematically investigated. An optimal carrier concentration range of around 5 ∼ 6 × 1020 cm−3, corresponding to the actual Yb filling fraction of around 0.21∼0.26, has been determined, which displays the highest thermoelectric performance in Y bxCo4Sb12 thermoelectric materials.

Grain Boundary Engineering for Achieving High Thermoelectric Performance in n‐Type Skutterudites

“…Thus, lattice thermal conductivity κ lat is obtained by subtracting κ ele from κ total and presented in Figure b. Compared with the results of Li et al, our present MS sample shows a relatively higher κ lat , caused by the different preparation methods. More importantly, κ lat of the other samples decreases somewhat despite the decreased Yb filling fraction.…”

“…Figure 5 shows the electrical transport properties of x %Sb‐MS samples. It should be mentioned that the dashed line in Figure a–c represents the Yb 0.29 Co 4 Sb 12.05 sample (actual composition) prepared by melting spinning and spark plasma sintering (SPS) method that exhibits similar properties with our MS sample (Yb 0.29 Co 4 Sb 11.97 ) . The electrical resistivity ρ of all the samples exhibits the typical degenerate‐semiconductor behavior (Figure a), attributed to the high filling fraction of Yb.…”

“…a) Electrical resistivity, b) Seebeck coefficient, and c) power factor for Yb 0.3 Co 4 Sb 12 + x %Sb ( x = 0, 10, 20, and 30). The dashed lines in (a)–(c) represent the Yb 0.29 Co 4 Sb 12.05 sample (actual composition) prepared by melting spinning and spark plasma sintering (SPS) method . d) Power factor in comparison with other advanced filled Skutterudites …”

High Performance Thermoelectric Materials: Progress and Their Applications

“…As a consequence, S can be increased while σ will not be significantly reduced. [28,214] Figure 7d shows an example of the enhanced S 2 σ via energy filtering by manipulating grain boundaries [28] of Yb-filled CoSb 3 compared with its counterparts [215] without energy filters. [28,214] Figure 7d shows an example of the enhanced S 2 σ via energy filtering by manipulating grain boundaries [28] of Yb-filled CoSb 3 compared with its counterparts [215] without energy filters.…”

“…Schematic examples of the potential barrier for a) low energy carrier (holes in here, for example) and b) minor carriers. [215] www.advancedsciencenews.com conductivity and providing phonon scattering to enhance ZT. [131] Copyright 2014, AIP Publishing.…”