Zintl-phase Eu<sub>2</sub>ZnSb<sub>2</sub>: A promising thermoelectric material with ultralow thermal conductivity.

Chen, Chen; Xue, Wenhua; Li, Shan; Zhang, Zongwei; Li, Xiaofang; Wang, Xinyu; Liu, Yijie; Sui, Jiehe et al. · Proc Natl Acad Sci U S A · 2019

basic_science · Level V

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Abstract

Zintl compounds are considered to be potential thermoelectric materials due to their "phonon glass electron crystal" (PGEC) structure. A promising Zintl-phase thermoelectric material, 2-1-2-type Eu<sub>2</sub>ZnSb<sub>2</sub> (<i>P</i>6<sub>3</sub>/<i>mmc</i>), was prepared and investigated. The extremely low lattice thermal conductivity is attributed to the external Eu atomic layers inserted in the [Zn<sub>2</sub>Sb<sub>2</sub>]<sup>2-</sup> network in the structure of 1-2-2-type EuZn<sub>2</sub>Sb<sub>2</sub> [Formula: see text], as well as the abundant inversion domain boundary. By regulating the Zn deficiency, the electrical properties are significantly enhanced, and the maximum <i>ZT</i> value reaches ∼1.0 at 823 K for Eu<sub>2</sub>Zn<sub>0.98</sub>Sb<sub>2</sub> Our discovery provides a class of Zintl thermoelectric materials applicable in the medium-temperature range.