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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ga2Te3 by Materials Project

Ga2Te3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four Te2- atoms to form corner-sharing GaTe4 tetrahedra. There are one shorter (2.59 Å) and three longer (2.71 Å) Ga–Te bond lengths. In the second Ga3+ site, Ga3+ is bonded to four Te2- atoms to form corner-sharing GaTe4 tetrahedra. There are a spread of Ga–Te bond distances ranging from 2.60–2.72 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a water-like geometry to two Ga3+ atoms. In the second Te2- site, Te2- is bonded in a trigonal non-coplanar geometry to three Ga3+ atoms. In the third Te2- site, Te2- is bonded in a trigonal non-coplanar geometry to three Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Extraordinary role of Zn in enhancing thermoelectric performance of Ga-doped n-type PbTe

Although Ga doping can weaken the electron phonon coupling in n-type PbTe, Ga-doped PbTe has a relatively low carrier concentration (n) and high lattice thermal conductivity (κ lat ), resulting in a lower figure of merit (ZT) compared with those of other top-performing n-type PbTe-based thermoelectric materials. Herein, we report the extraordinary role of Zn in enhancing the thermoelectric performance of Ga-doped PbTe. It is discovered that Zn can simultaneously improve the electronic transport properties and decrease the κlat of Ga-doped PbTe, thereby affording a record high ZT avg ~ 1.26 at 400–873 K, with a maximum ZT value of 1.55 at 723 K. The isoelectronic substitution of Zn for Pb in Ga-doped PbTe increases the electrical conductivity and n by inducing the nucleation and growth of Ga 2 Te 3 in the second phase. The formation of Ga 2 Te 3 results in nonstoichiometry and Te deficiency in the PbTe matrix, which increases the number of electron carriers. Additionally, discordant Zn and Ga atoms with displacing off-center from the ideal octahedral positions, as well as Ga 2 Te 3 nanocrystals ranging from 30 to 200 nm coherently embedded into the PbTe matrix effectively weaken the phonon modes and scatter heat-carrying phonons, resulting in a significant reduction in κ lat .

36 MATERIALS SCIENCE↗