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As a most promising mid‐temperature thermoelectric material, CoSb3‐based bulk material exhibits an applicable figure‐of‐merit (ZT) of more than one. However, their fabrication is historically time‐consuming due to the long‐time solid‐state phase transitions from CoSb2 to CoSb3. To overcome this challenge, here, a fast one‐step process is developed to fabricate n‐type Yb‐doped CoSb3 with stable ZT of 1.12 at 765 K in <5 h. Experiments confirm Yb promotes peritectic reactions of CoSb + Liquid → CoSb2 and CoSb2 + Liquid → CoSb3, optimizes power factor, and suppresses thermal conductivity. Moreover, the dense grains, induced by the one‐step crystallization, result in outstanding mechanical properties with a Young's modulus of 171.4 GPa and a hardness of 8.8 GPa in the Yb‐doped CoSb3. This study indicates that the fast one‐step fabrication route can effectively promote the practical applications of CoSb3‐based thermoelectrics and provide guidance for thermoelectric fabrication via rational phase design. [ABSTRACT FROM AUTHOR]

• A two-step method was utilized to synthesize multi-element doped Ce 0.3 Ni 1.5 Co 2.5 Sb 12 film efficiently. • Well-crystallized CoSb 3 and CeSb coexisted, leading to a positive effect on electrical properties. • The maximum value of S and PF reach −250 μV/K and 5275 μW/(mK2) for Ce 0.3 Ni 1.5 Co 2.5 Sb 12 film at 673 K. The skutterudite CoSb 3 has been widely concerned, as one of the most studied candidate materials for thermoelectric applications. Here, n-type bulk skutterudite Ce 0.3 Ni 1.5 Co 2.5 Sb 12 was successfully prepared under TGZM effect and its thin film deposited by PLD on single crystal Si substrate, to further understand the effect of microstructure and the electrical transport mechanism on the thermoelectric properties from bulk to thin film. It is found that two phases of Sb and CoSb 3 coexist in bulk sample, while abundant nano-granular structures with well-crystallized CoSb 3 and little of CeSb generate in the film. As a result, the maximum value of S and PF reach −250 μV/K and 5275 μW/(mK2) for film sample at 673 K. The PF value of film is four times higher than that of the bulk sample. This provides a novel avenue to increase the thermoelectric properties of skutterudite. [ABSTRACT FROM AUTHOR]

Skutterudite compounds, the structure of "phonon glass electron crystal" (PGEC), possess excellent thermoelectric properties. Here, temperature gradient zone melting combined with hot pressing technique (TGZM-HP) was employed to synthesize n-type skutterudite Ce x Ni 1.5 Co 2.5 Sb 12 thermoelectric material. By doping element Ce, the carrier concentration of the alloy was optimized efficiently and the total thermal conductivity declined. For the TGZM-HP Ce 0.6 Ni 1.5 Co 2.5 Sb 12 alloy, the power factor PF reaches to 1350 μW/(mK2), and the lattice thermal conductivity is dropped to 1.62 Wm−1K1 at 850 K, corresponding to an improved figure of merit ZT of 0.45. Importantly, compared with the traditional synthesis methods, this technique can precisely control the formation of thermometric phase and the preparation time is reduced remarkably. • A novel approach named TGZM-HP is proposed to synthesize single-phase CoSb 3 efficiently. • A low thermal conductivity of 2.76 Wm−1K-1 was obtained for the Ce 0.6 TGZM-HP alloy at 884 K. • It is convenient for further understanding "phonon glass electron crystal" (PGEC) structure. [ABSTRACT FROM AUTHOR]

Skutterudites based on CoSb 3 are considered potential candidates in thermoelectric applications in the field of mid-temperature power generation. The annealing process necessitates more than a week to complete the peritectic phase transition for traditional melting-quenching-annealing-sintering methods. Herein, a new strategy combining the temperature gradient zone melting process with hot pressing (TGZM-HP) was successfully employed to synthesize YbFe-doped p-type CoSb 3 in a shorter time. The resulting samples show enhanced thermoelectric properties compared to TGZM-grown ones, especially in the case of 1 at.% YbFe-doped CoSb 3. This compound exhibits a maximal Seebeck coefficient of 166.3 μVK−1 and a power factor of 1.8 mWm−1K−2 at 723 K, showing an increase in these values of 25% and 51%, respectively. Moreover, phonon scattering appears to be enhanced due to the significant reduction in the grain size of the TGZM-HP samples, resulting in a minimum thermal conductivity of 2.71 Wm−1K−1. A dimensionless figure of merit (ZT) of 0.48 was obtained for 1 at.% YbFe-doped CoSb 3. This value is 1.6 times larger than that measured for TGZM-grown CoSb 3. This work provides an alternative strategy to fabricate skutterudite materials and foster their development. [ABSTRACT FROM AUTHOR]

Based on the Boltzmann transport theory combined with first-principles calculations, we analyze the lattice anharmonicity of SnTe and the respective contributions of the lattice thermal conductivity (κ L) from six different phonon modes. The Grüneisen parameter (γ), three-phonon scattering phase space (SPS), phonon lifetime (τ), and phonon velocity (v) were obtained quantitatively. These calculations indicate that large τ with maximum value of 104 ps and high v of 4800 m/s for acoustic branches make the acoustic modes a major contributor to the high κ L of SnTe (～78% for acoustic branches and ～22% for Optical branches). Further, the dependence of κ L on phonon mean free path shows that designing nanostructures with characteristic length of less than 14.5 nm could be an effective way to decrease the κ L. In addition, we employed high-temperature gradient directional solidification technique to grow the SnTe single crystal and the measured κ L vaules of the single crystal match reasonably with the theoretical calculation results. • Lattice anharmonicity of SnTe was investigated based on first-principles calculations. • The respective contributions of κ L from six different phonon modes were computed quantitatively. • The theoretical calculation results of the κ L agree well with the experimental values of the single-crystal SnTe. • Designing nanostructures with characteristic length of less than 14.5 nm could be an effective way to decrease the κ L. [ABSTRACT FROM AUTHOR]