Ultralow lattice thermal conductivity enables high thermoelectric performance in BaAg2Te2 alloys

Due to the intrinsic low lattice thermal conductivity (kappa(L)), AB(2)X(2) Zintl compounds with a P3-M1 crystal structure have been demonstrated as potential thermoelectric candidates. Recently, a novel AB(2)X(2) compound with a Pnma crystal structure has been revealed to possess an even lower kappa(L), which motivates this work to focus on BaAg2Te2 for its potential for thermoelectric applications. Impressively, pristine BaAg(2)Te(2 )shows a kappa(L ) lower than similar to 0.3 W/m-K in the entire temperature range, being the lowest one ever reported in AB(2)X(2) thermoelectrics. Theoretically, such a low kappa(L ) comes from intrinsically strong anharmonicity and low sound velocity. With help of Cu-alloying at Ag site for increasing carrier concentration and for reducing kappa(L), a peak zT up to similar to 1.3 is achieved in BaAgCuTe2 alloy, and its single-leg device with Ag as the electrode enables an output power of similar to 120 mW under a temperature difference of similar to 375 K, demonstrating BaAg2Te2 based alloys as promising thermoelectric materials. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study focuses on the potential thermoelectric applications of BaAg2Te2, a compound with a Pnma crystal structure that exhibits a remarkably low lattice thermal conductivity. By alloying with Cu at the Ag site, the carrier concentration can be increased and the thermal conductivity can be reduced, leading to enhanced thermoelectric performance.