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There is evidence that magnetism can potentially increase the thermopower of materials, most likely due to magnon scattering, suggesting the incorporation of intrinsic magnetic semiconductors in non-magnetic thermoelectric materials. Here, samples of p-type Bi0.5Sb1.5Te3 with 10 at. % excess Te are ball-milled with varying ratios of the antiferromagnetic semiconductor CrSb (0, 0.125, 0.5, and 1 wt. %) to prepare bulk samples by spark plasma sintering technique. The thermopower of samples containing CrSb is increased due to an increase in the effective mass of the charge carriers, indicating that there is a drag effect originating from the magnetic particles. However, this was at the expense of reduced electrical conductivity caused by reduced charge carrier mobility. While overall only marginal improvements in power factors were observed, these samples exhibited significantly lower thermal conductivity compared to the single-phase material. As a result, a peak zT value of ∼1.4 was achieved at 325 K for the sample with 0.125 wt. % CrSb. These results highlight the potential of incorporating magnetic secondary phases to enhance the thermoelectric performance of materials. [ABSTRACT FROM AUTHOR]

Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics (PFmax=$PF_{\text{max}} =$ 21.5 µW cm−1 K−2 and zTmax=$zT_{\text{max}} =$ 0.5 at 1100 K in Zn0.96Al0.04O${\rm Zn}_{0.96} {\rm Al}_{0.04}{\rm O}$) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics. [ABSTRACT FROM AUTHOR]

In-filled skutterudites InxCo4Sb12 have attracted much attention due to their relatively high thermoelectric performance, which, in turn, is attributed to the In atoms acting as rattlers in the skutterudite voids and to the formation of InSb precipitates when the In solubility limit is exceeded (0.22 ≤ xmax ≤ 0.27). In this work, to suppress the formation of the unwanted CoSb2 phase and favor the formation of InSb precipitates, the following composition of In1Co4Sb12+δ with In concentration much higher than the solubility limit and Sb overstoichiometry was used. Three sets of bulk specimens with a nominal composition of In1Co4Sb12+δ were synthesized by conventional induction melting followed by (1) ball milling (BM) and spark plasma sintering (SPS), (2) BM and SPS followed by high-temperature annealing, and (3) melt spinning and SPS. The utilization of different sample preparation methods and processing conditions leads to samples with different microstructures and InSb precipitates of different shapes, sizes, and distributions. Thus, for all samples with the same nominal composition of In1Co4Sb12+δ, zTmax varies from 0.7 to 1.3 at 673 K only because of microstructural modification. A maximum zT value of around 1.3 was obtained at 673 K for the sample prepared using induction melting followed by annealing, melt spinning, and SPS. [ABSTRACT FROM AUTHOR]

Bismuth chalcogenides are promising materials for thermoelectric (TE) application due to their high power factor (product of the square of the Seebeck coefficient and electrical conductivity). However, their high thermal conductivity is an issue of concern. Single doping has proven to be useful in improving TE performance in recent years. Here, it is shown that dual isovalent doping shows the synergistic effect of thermal conductivity reduction and electron density control. The insertion of large atoms in the layered Bi2Te3 structure distorts the crystal lattice and contributes significantly to phonon scattering. The ultralow thermal conductivity (KT = 0.35 W m−1 K−1 at 473 K) compensates for the low power factor and thus enhances TE performance. The density functional theory electronic structure calculation results reveal deep defects states in the valence band, which influences the electronic transport properties of the system. Therefore, the dual dopants (indium and antimony) show a coupled effect of improvement in the density of state near the Fermi level and reduction in the conduction band minimum, thus enhancing electron density. Numerically, it is demonstrated that the dual doping favors acoustic phonon scattering and thus drastically reduces the thermal conductivity. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is widely used for the consolidation of different materials. Copper-based pseudo alloys have found a variety of applications including as electrodes in vacuum interrupters of high-voltage electric circuits. How does the kinetics of SPS consolidation for such alloys depend on the heating rate? Do SPS kinetics depend on the microstructure of the media to be sintered? These questions were addressed by the investigation of SPS kinetics in the heating rate range of 0.1 to 50 K/s. The latter conditions were achieved through flash spark plasma sintering (FSPS). We also compared the sintering kinetics for the conventional copper–chromium mixture and for the mechanically induced copper/chromium nanostructured particles. It was shown that, under FSPS conditions, the observed maximum consolidation rates were 20–30 times higher than that for conventional SPS with a heating rate of 100 K/min. Under the investigated conditions, the sintering rate for mechanically induced composite Cu/Cr particles was 2–4 times higher compared to the conventional Cu + Cr mixtures. The apparent sintering activation energy for the Cu/Cr powder was twice less than that for Cu–Cr mixture. It was concluded that the FSPS of nanostructured powders is an efficient approach for the fabrication of pseudo-alloys. [ABSTRACT FROM AUTHOR]