Zintl-phase Eu2ZnSb2: A promising thermoelectric material with ultralow thermal conductivity

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 2 ZnSb 2 ( P 6 3 / mmc ), was prepared and investigated. The extremely low lattice thermal conductivity is attributed to the external Eu atomic layers inserted in the [Zn 2 Sb 2 ] 2- network in the structure of 1-2-2–type EuZn 2 Sb 2 ( P 3 ¯ m 1 ) , as well as the abundant inversion domain boundary. By regulating the Zn deficiency, the electrical properties are significantly enhanced, and the maximum ZT value reaches ∼1.0 at 823 K for Eu 2 Zn 0.98 Sb 2 . Our discovery provides a class of Zintl thermoelectric materials applicable in the medium-temperature range.