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In this work we have observed the beneficial effect from the solid solution formation on the thermoelectric performance of (Cu 2(1 − x ) Sb 2 x Te)(Ga 2 Te 3 ) 3 upon Sb substitution for Cu. This substitution allows the different occupations of Sb in the crystal lattice, i.e. Sb at Cu sites with x ≤ 0.05 and at Ga sides with x ≥ 0.05, which has resulted in the Pisarenko relation does not exactly capture the measured Seebeck coefficient under assumed effective masses m *. The reduction of the lattice thermal conductivity ( κ L ) has been quantified within the temperature range from room temperature to 723 K. Over the entire composition range, the κ L value is reduced by 33% and 25% at temperature 723 K and 580 K, respectively. This observation is in a good agreement with the theoretical calculation based on the Callaway model used in the solid solutions. Along with the increasing of the mobility and electrical conductivity, the thermoelectric performance has been improved with the highest ZT value of 0.58 at 723 K, which is about double the value of intrinsic (Cu 2 Te)(Ga 2 Te 3 ) 3 . [ABSTRACT FROM AUTHOR]

MoS 2 nanosheets with size of several-hundred nanometers were prepared by a hydrothermal intercalation/exfoliation method, then MoS 2 /Bi 2 Te 3 composite nanopowders were prepared by a microwave-assisted wet chemical method using the MoS 2 nanosheets, TeO 2 , Bi(NO 3 ) 3 ·5H 2 O, KOH and ethylene glycol as raw materials. Bulk MoS 2 /Bi 2 Te 3 nanocomposites were prepared by hot pressing the MoS 2 /Bi 2 Te 3 composite nanopowders with MoS 2 nanosheet content ranging from 0 to 17 wt% at 80 MPa and 648 K in vacuum. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicate that MoS 2 and Bi 2 Te 3 did not react each other during the hot pressing. FESEM observation reveals that the MoS 2 /Bi 2 Te 3 composite samples had a more compact microstructure than the pristine Bi 2 Te 3 bulk sample. The MoS 2 phase was relatively randomly dispersed in the composite. At a given temperature, the electrical conductivity of the composites increases first then decreases as the MoS 2 content increases, whereas the Seebeck coefficient of the bulk nanocomposites does not change much. A highest power factor, ~18.3 μW cm −1 K −2 which is about 30% higher than that of pristine Bi 2 Te 3 sample, at 319 K has been achieved from a nanocomposite sample containing 6 wt% MoS 2 . [ABSTRACT FROM AUTHOR]

As a potential thermoelectric (TE) material, the high lattice thermal conductivity and relatively low weighted mobility severely limit TE property optimization of InSb binary compound. In this paper, we substituted In of InSb with Ga and systematically investigated the effect of Ga alloying on the Seebeck coefficient, electrical conductivity and lattice thermal conductivity of InSb between 300 K and 770 K. We found that Ga alloying simultaneously reduced the lattice thermal conductivity and optimized the weighted mobility of InSb. The lattice thermal conductivity has been analyzed using Abeles model to gain more insight on the roles of Ga in In 1- x Ga x Sb( x  = 0, 0.1, 0.15, 0.2) solid solution. The synergetic effect of Ga alloying on the electron and phonon transport leads to a marked enhancement in TE potential of InSb. The dimensionless figures of merit of InSb and In 0.8 Ga 0.2 Sb reach, respectively, 0.54 and 0.52 at 770 K. [ABSTRACT FROM AUTHOR]

In Ga 2 Te 3 -rich quasibinary Cd (3 − 3 m ) Ga 2 m Te 3 ( m = 0.75–0.98) system there are two physical phenomena: structural vacancy ( V ) and its related cationic interdiffusion. The former is able to simultaneously govern the carrier, phonon transportations and the bandgap, while the latter merely facilitates the transportation of carrier to some extent. Accordingly, there are multiple transportation behaviors coexisting at a certain m value in this system. These behaviors, which have not only enhanced the carrier concentration ( n ), but have also increased the entropy of the lattice as m value increases, yield the highest thermoelectric figure of merit ( ZT ) of 0.55 at 682 K for m = 0.98. [ABSTRACT FROM AUTHOR]

Thin-film STEGs (solar thermoelectric generators) show promise in effective use of solar energy as a power supply for wireless sensors and microscale devices. This paper reports a simulation procedure that aims to identify desirable heat flow and temperature distribution to improve the performance of thin-film STEGs. The temperature distribution, heat flux, and voltage of a thin-film STEG are simulated using the finite element method, resulting in an optimal design of the substrate, heat conductive layer, and thermoelectric legs of thin-film STEGs. The effect of air convection on the STEG's performance is also studied. Based on the simulation, a thin-film STEG was designed and fabricated, which exhibits an open-circuit voltage of 22 mV. In addition, the experimental results demonstrate that the measured temperature distribution is in good agreement with the simulated result. To minimize the heat loss from the passive region of the device, an improved design was created in an attempt to confine the heat flow within the thermoelectric legs. This improved design resulted in a 21.4% increase of the output voltage. [ABSTRACT FROM AUTHOR]

The ZT value is increased to ~1.05 at 723 K owing to the significant enhancement of the power factor and reduction in lattice thermal conductivity, making the ZT value of Ag 8 Ge 0.9 Sn 0.1 Se 6 stands among the highest in the Ag 8 GeSe 6 system at present. [Display omitted] • The carrier concentration and power factor are greatly improved upon Sn incorporation. • The lattice thermal conductivity decreases simultaneously. • The ZT value of Ag 8 Ge 0.9 Sn 0.1 Se 6 is increased to ~1.05. Argyrodite compound Ag 8 GeSe 6 (AGS) as one of the superionic conductors possesses unique crystal structures: the rigid anionic framework [GeSe 4 ]4- and mobile cation (Ag). Hence its lattice thermal conductivity is rather low due to the action of the mobile cation (Ag). However, this compound has neither high carrier concentration (0.15 × 1016 cm−3 at 300 K and 0.61 × 1016 cm−3 at 370 K) nor high thermoelectric performance (the figure of the merit (ZT) of<0.4). So in this work, we enhance the carrier concentration by more than one order of magnitude at 373 K through the band structure engineering via the substitution of Sn for Ge. In the mean time, the lattice thermal conductivity (κ L) reduces from 0.26 W/mK to 0.16 W/mK at 750 K. As a consequence, the ZT value of Ag 8 Ge 0.9 Sn 0.1 Se 6 is boosted to ~ 1.05. This value is about 2.8 times that of the pristine AGS (0.38 at 750 K) and stands among the highest in this family so far. The above results confirm that the isoelectronic substitution of Sn for Ge in the anionic framework of AGS is an effective way to realize its high TE performance. [ABSTRACT FROM AUTHOR]