Zintl-phase Eu ₂ ZnSb ₂ : A promising thermoelectric material with ultralow thermal conductivity

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 Eu₂ZnSb₂ (<i>P</i>6₃/<i>mmc</i>), was prepared and investigated. The extremely low lattice thermal conductivity is attributed to the external Eu atomic layers inserted in the [Zn₂Sb₂]^2- network in the structure of 1-2-2-type EuZn₂Sb₂ [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 Eu₂Zn_0.98Sb₂ Our discovery provides a class of Zintl thermoelectric materials applicable in the medium-temperature range.