Thermoelectric Zintl Compound In_1−xGa_xTe: Pure Acoustic Phonon Scattering and Dopant‐Induced Deformation Potential Reduction and Lattice Shrink

Abstract

We report a Zintl phase thermoelectric material, coarse grain-In 0.99 Ga 0.01 Te, achieving a ZT peak of 1.2 at 648 K and an average ZT = 0.8 in 300-650 K, which outperforms all the known InTe-based materials to date. The synergistic optimization of electronic property and phonon transport are achieved by the purification of grain boundary scattering, together with the Ga-doping-induced weak phonon-electron coupling, which enhances the carrier mobility and carrier concentration simultaneously and consequently gives a remarkably increased power factor of 8.9 μW cm À 1 K À 2 . The DFT phonon calculations indicate the dopant reduces the deformation potential coefficient and induces the lattice shrink, which reduces significantly the acoustic cutoff frequency, and enhances the scattering phase space. Moreover, the bonding hierarchy leads to the dense intragranular dislocation arrays, which suppresses the lattice thermal conductivity further and induces an ultralow lattice thermal conductivity (0.

Crystal Structure, Electronic Transport, and Improved Thermoelectric Properties of Doped InTe

“…Figure f shows that the highest peak zT value at 725 K is 0.64, obtained in the In 0.99 Sn 0.01 Te sample, more than 50% higher than 0.41 at 725 K in the undoped sample. The peak zT of the In 0.99 Sn 0.01 Te sample in this study is comparable with those of many reported doped InTe polycrystalline samples ,,− but lower than those of In 0.999 Pb 0.001 Te and In 0.99 Ga 0.01 Te samples.…”

Rare three-valence-band convergence leading to ultrahigh thermoelectric performance in all-scale hierarchical cubic SnTe

“…The representative frequency of 1.0 THz in SnTe is responsible for 90% of the cumulative κ L , indicating that the low-frequency phonon in SnTe dominates the thermal transport. This scenario further demonstrates that the Cd-induced low-frequency optical phonons and phonon softening significantly contribute to κ L reduction, and a similar phenomenon has also been observed in other TE compounds, such as InTe, 49 CsCu 4 Se 3 , 50 and YbFe 4 Sb 12 , 51 exhibiting ultralow lattice thermal conductivity.…”

“…21 These results strongly manifest that sufficient κ L reduction can be realized in the solid solution of (SnTe) 1− x (MnCd 1− y Ge y Te 2 ) x by introducing abundant hierarchical nano/mesostructures and low-frequency optical modes to scatter phonons at all scales. ZT is proportional to the quality factor ( B ), which can be calculated with eqn (7): 49 where μ W is an n H -independent quantity, which can essentially quantify the number and mobility parameter ( μ 0 ) of conduction channels for charge carrier transport. 68 Consequently, the decoupling effect ( i.e.…”

Realizing Enhanced Thermoelectric Performance in Zintl-Phase SrCuSb by Reducing the Thermal Conductivity

“…Thermoelectric materials play a very important role in applications such as waste heat energy conversion, , solid-state cooling, and power supplies . The conversion efficiency is mainly determined by the figure of merit zT ( zT = ( S 2 σ/κ) T , where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature). − Zintl-phase compounds have been considered as promising thermoelectric materials due to their “phonon-glass electron-crystal” structure. − The anion groups connected by covalent bonds in the crystal structure mainly play the role of carrier transport, while the cations that form ionic bonds with the anion groups mainly play the role of scattering phonons. Up to now, a series of Zintl compounds have been reported as promising thermoelectric materials, such as Yb 14 MnSb 11 , − YbCd 2 Sb 2 , , Eu 2 ZnSb 2 , , CaZn 0.4 Ag 0.2 Sb, Ca 10 GdCdSb 9 , Ca 9 Zn 4+ x Sb 9 , KGaSb 4 , BaAg 2 Te 2 , etc .…”