Search

The rational synthesis of high‐performance thermoelectric (TE) materials guided by theoretical design is still in its infancy. Here by computationally exploiting the possibilities of materials' dopability and hence the electron–phonon transport/scattering, a new defective compound, AgGaTe2, with simultaneous Ag deficiency and isoelectronic substitution of In on Ga‐site (InGa) is predicted, and its high performance is then confirmed via experiments. Using density functional theory and density functional perturbation theory calculations, it is identified that controlled defects viz. Ag vacancy and In substitution in AgGaTe2 system can lead to extremely low lattice thermal conductivity (κL) of around 0.13 WK−1 m−1 at 850 K. This ultralow κL results from both the Ag vacancy that serves as a better rattler and the extra phonon scattering due to the defect induced internal lattice distortion (ψ). The synthesized compounds Ag0.85Ga1−xInxTe2 (x = 0–0.3) indeed achieve the extremely low κL (0.08 WK−1 m−1 for x = 0.15). As a result, the highest TE figure of merit (ZT) of 1.44 is obtained, which is the highest recorded value for silver‐based ternary chalcopyrite semiconductors to date. [ABSTRACT FROM AUTHOR]

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]

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]

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]