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α-MgAgSb is taken as the p-type leg material for recently focused Mg-based thermoelectric devices because of the high thermoelectric performance near room temperature. However, the thermoelectric performance of α-MgAgSb is inhibited by the existence of the Ag-rich second phase. The ordinary methods like carrier concentration optimization and minimizing lattice thermal conductivity were nearly invalid because of the extremely low doping level for heteroatoms and intrinsically low lattice thermal conductivity. The crystal structure of α-MgAgSb can be viewed as Ag atom filled in half distorted hexahedron in the distorted rock salt skeleton formed by the Mg–Sb sublattice. In this work, by replacing the smaller Mg in the sublattice with Pb, the volume of the distorted hexahedron is effectively expanded to accommodate Ag atoms and then lead to the re-dissolution of Ag-rich second phase in the matrix. In addition, as Ag is the main source of low-frequency phonons, the enhanced lattice anharmonicity by Pb doping leads to stronger scattering of phonons in the distorted hexahedron and results in 20% reduction of lattice thermal conductivity in the temperature range of 300–500 K. Finally, the figure of merit zT is enhanced by ∼40% in the whole temperature range, demonstrating that lattice management is a promising method for the optimization of α-MgAgSb materials. [ABSTRACT FROM AUTHOR]

The different masses, ionic radii, and chemical valences of the nonequivalent crystallographic sites of thermoelectric (TE) compounds provide an effective way to modulate the thermoelectric performance by selective substitution. In this work, the selective substitution of In+ by Pb for the binary InTe material monotonically reduces the carrier concentration, which is greatly beneficial to the mechanism investigation of serious grain boundary scattering (GBS). This is the first time this point has been mentioned with regard to InTe material. As a result, we found that GBS was dominated by the grain size when the carrier concentration was higher than 0.7 × 1019 cm−3 but was inversely governed by the carrier concentration when the carrier was situated at a lower density. In particular, the occupation of Pb on the targeted In+ site could further reduce the lattice thermal conductivity. Finally, In0.9999Pb0.0001Te achieved the improved power factor and average zT value, which could contribute to high-power generation below a medium temperature. This effect of increasing the carrier concentration on the suppression of GBS sheds light on the possibility of improving electron mobility by increasing the carrier concentration. [ABSTRACT FROM AUTHOR]

La3Te4-based rare-earth telluride is a kind of n-type high-temperature thermoelectric (TE) material with an operational temperature of up to 1273 K, which is a promising candidate for thermoelectric generators. In this work, the Sm substitution in La3−xSmxTe4/Ni composites is reported. The electrical transport property of La3−xSmxTe4 is modified by reducing carrier concentration due to the substitution of Sm2+ for La3+. The electric thermal conductivity decreases by 90% due to carrier concentration reduction, which mainly contributes to a reduction in total thermal conductivity. Lattice thermal conductivity also decreases by point-defect scattering by Sm doping. Meanwhile, based on our previous study, compositing nickel improves the thermal stability of the La3 − xSmxTe4 matrix. Finally, combined with carrier concentration optimization and the decreased thermal conductivity, a maximum zT of 1.1 at 1273 K and an average zTave value of 0.8 over 600 K–1273 K were achieved in La2.315Sm0.685Te4/10 vol.% Ni composite, which is among the highest TE performance reported in La3Te4 compounds. [ABSTRACT FROM AUTHOR]

In‐grain dislocation‐induced lattice strain fluctuations are recently revealed as an effective avenue for minimizing the lattice thermal conductivity. This effect could be integratable with electronic enhancements such as by band convergence, for a great advancement in thermoelectric performance. This motivates the current work to focus on the thermoelectric enhancements of p‐type PbTe alloys, where monotelluride‐alloying and Na‐doping are used for a simultaneous manipulation on both dislocation and band structures. As confirmed by synchrotron X‐ray diffractions and Raman measurements, the resultant dense in‐grain dislocations induce lattice strain fluctuations for broadening the phonon dispersion, leading to an exceptionally low lattice thermal conductivity of ≈0. 4 W m‐K−1. Band structure calculations reveal the convergence of valence bands due to monotelluride‐alloying. Eventually, the integration of both electronic and thermal improvements lead to a realization of an extraordinary figure of merit zT of ≈2.5 in Na0.03Eu0.03Cd0.03Pb0.91Te alloy at 850 K. [ABSTRACT FROM AUTHOR]

Abstract: Ab-initio calculations of the resonant modes and frequencies for a number of possible fillers in p-type RFe3CoSb12 and RFe4Sb12 were carried out. The results indicate that, although the exact values of fillers’ resonant frequencies in p-type skutterudites are somewhat different from those in n-type Co-based skutterudites, the Einstein-like resonant modes of the fillers are similar to those in n-type materials. Experimentally, several pairs of the fillers were selected and double-filled p-type skutterudite compounds RxMy Fe3CoSb12 (R, M = Ba, Ce, Nd, and Yb) were successfully synthesized. The reduction in the lattice thermal conductivity was realized by extending the range of resonant frequencies. As a result, enhanced ZT values above unity were achieved in these double-filled p-type skutterudites. [Copyright &y& Elsevier]

• Influence of Peltier heat on test accuracy of Transient Electro-thermal is studied. • High accuracy test for thermal conductivity of TE films can be achieved in TPET. • The heat transfer model to measure double-layers film in TPET is established. Accurate and rapid measurement of thermal conductivity of thin films has been a challenge so far in the field of thermoelectric (TE) materials and devices. Herein, we proposed to use a transient photo-electro-thermal (TPET) technique to measure the thermal conductivity of TE thin-films with convenience. Combining theoretical and experimental methods, we found that the TPET technique using laser beam heating can significantly reduce the influence of Peltier effect and thus achieve high test accuracy. The measurement uncertainty of TPET technique for TE films can be depressed below 10%. Furthermore, this method is not only applicable for free-standing thin film, but also for thin film deposited on as-known substrates. Finally, thermal conductivity of several films including p -type Bi 0.5 Sb 1.5 Te 3 , n -type Ag 2 Se, and n -type Bi 2 Te 3 deposited on PI film at different temperature are accurately measured, which demonstrates the wide applicability of TPET technique on semiconductor films. [ABSTRACT FROM AUTHOR]

High performance flexible thermoelectric thin films are desired for power generation of flexible thermoelectric device. Thermoelectric performance of (Sb,Bi) 2 Te 3 films are determined by the Te content in the matrix as anti-site defect dominates the carrier concentration. By controlling the Te target co-sputtering power, annealing temperature and time, not only the film in-plane orientation is enhanced, the carrier concentration is also effectively controlled in this work. Through a systematically investigation of Te content dependence of the thermoelectric performance, the carrier concentration and orientation is optimized through tuning Te content, and a high power factor of ∼32 μ W/cm-K2 for Sb 2 Te 3 film, ∼36 μ W/cm-K2 for Bi 0.5 Sb 1.5 Te 3 film is realized in in-plane orientation. Besides, The thermal conductivity along in-plane direction is determined by photon-electro-thermal (TPET) technique, and the final zT values are ∼0.49 for Sb 2 Te 3 , and ∼0.58 for Bi 0.5 Sb 1.5 Te 3 films at room temperature, respectively. • Enhanced in-plane orientation by Te co-sputter. • Systematically Te content control and Carrier concentration optimization. • In-plane thermal conductivity measurement by photon-electro-thermal (TPET) technique. • High power factor ∼32 μ W/cm-K2 for Sb 2 Te 3 film, ∼36 μ W/cm-K2 for Bi 0.5 Sb 1.5 Te 3 film. [ABSTRACT FROM AUTHOR]

• The power density is higher than other thin-film thermoelectric generator. • Substrate with unique structure resulted in increase of both output voltage and the maximum output power. • A comprehensive 3D simulation with variable parameter was developed. [Display omitted] Thermoelectric generators can be used as energy harvesting for power supply in Internet of Thing sensors. Here, material properties and geometry parameters were investigated to improve the annular thin-film thermoelectric generator (ATTEG) output performances. The as-deposited and annealed n-type Bi 2 Te 2.7 Se 0.3 and p-type Bi 0.5 Sb 1.5 Te 3 were deposited by radio frequency magnetron sputtering which resulted in higher Seebeck coefficient and electrical conductivity of annealed thin films. The temperature distributions and output performances in ATTEG were calculated using numerical simulation to identify the geometry parameters. The results showed that thinner substrate with higher output performances, larger legs number with higher output voltage, and a peak point in the maximum output power was observed for the effect of the angle ratio of p-type leg to n-type leg with optimal value of 1. We fabricated ATTEGs with different TE legs to identify the machining accuracy, and the ATTEG with 12 legs resulted in output voltage of 27.7 mV, the maximum output power of 169.0 nW and power density of 127.39 n W ∕ cm 2 at a temperature difference of 23 K. Hollowing and nicking on substrate were proposed as further improvement, and resulted in increasement of 6.6% in output voltage and 13.6% in the maximum output power. [ABSTRACT FROM AUTHOR]

Abstract: p-type Sn-doped CoSb3-based skutterudite compounds have been prepared using melting–quenching–annealing method and spark plasma sintering technique. Sn atoms in our samples are completely soluted on Sb-site with a fixed charge state and non-magnetic feature, providing a better choice to ascertain the effect of element doping at the [Co4Sb12] framework on the electrical and thermal transport properties in p-type skutterudites. Doping Sn at the framework introduces additional ionized impurity scattering to affect the electron transport greatly. Similar electrical transport properties between Ce0.2Co4Sb11.2Sn0.8 and Co4Sb11Sn0.6Te0.4 suggest that Ce fillers contribute little to the valence band edge. Filling Ce into the voids and doping Sn at the framework introduce additional phonon resonant and point defect scattering mechanisms, thereby reducing lattice thermal conductivity remarkably. Moreover, our data suggest that combining these two effects is more effective to suppress lattice thermal conductivity through scattering broad range of phonons with different frequencies. [ABSTRACT FROM AUTHOR]