Realizing high thermoelectric performance of Mg3(Sb, Bi)2 by Ho-Te dual-doping and synergistic transport engineering

Mg 3 (Sb, Bi) 2 is a promising mid- to low- temperature thermoelectric material owing to its earth-abundant composition. However, its performance is limited by low intrinsic carrier concentration and the inherent trade-off among thermoelectric parameters. Herein, large-grain sized Mg 3.01 Sb 1.3 Bi 0.69 Te 0.01 Ho 0.07 are fabricated via melting method at 1423 K using a tantalum-sealing technique. A high peak zT of 1.6 at 700 K is realized, along with a peak power factor of 24 μW cm −1 K −2 and a low κ L of 0.41 W m −1 K −1 . The superior performance originates from synergistic manipulation of electron and phonon transport. Ho doping optimizes carrier concentration up to 7.2 × 10 19 cm −3 due to its small electronegativity difference with Mg, while the large grain ensures high carrier mobility. Simultaneously, atomic-scale alloy disorder suppresses phonon propagation, resulting in a substantial reduction in lattice thermal conductivity. This work highlights the great potential of synergistic transport engineering for high-performance Mg 3 (Sb, Bi) 2 -based thermoelectric materials.