Maximized atomic disordering approach boost the thermoelectric performance of Mg2Sn through the self-compensation effect and steric effect

Atomic disordering was an effective strategy to reduce lattice thermal conductivity. In this work, the atomic disordering of Mg2-delta Sn1-xBix was maximized by both the charge self-compensation and steric effects. Due to the strong phonon scattering arose from substitutional defects Bis n and self-compensational vacancies V-Mg, an exclusively low lattice thermal conductivity of 1.38 W m(-1) K-1 was observed in the Mg2-delta Sn0.8Bi0.2 sample, corresponding to only 30% of Mg2Sn, while a 30% less than that of its counterpart Mg2-delta Sn0.8Bi0.2 (1.97 W m(-1) K-1). The EPMA result presents that the Mg2-delta Sn0.8Bi0.2 has a higher concentration of V-Mg than that of Mg2-delta Sn0.8Bi0.2, suggesting an apparent steric effect for the formation of V-Mg. Furthermore, the Mg vacancy and its induced lattice shrinkage also result in band convergence. Consequently, a high ZT of 1.14 was obtained at 500 degrees C in the Mg2-delta Sn0.8Bi0.2 sample, which is 52% higher than the conventionally doped Mg2Sn0.99Bi0.01, while comparable with the Mg2-delta Sn0.8Bi0.2. This work provides new insight into tuning thermoelectric transport properties through the atomic disorder strategy. (C) 2021 Published by Elsevier Ltd on behalf of Acta Materialia Inc.

Automated summary

Atomic disordering was maximized in Mg2-delta Sn1-xBix through charge self-compensation and steric effects, leading to a significantly low lattice thermal conductivity. The Mg2-delta Sn0.8Bi0.2 sample showed a high ZT of 1.14 at 500 degrees C, indicating the effectiveness of tuning thermoelectric transport properties through atomic disorder strategy.