Dislocation Introduction via Domain Engineering in Mg ₂ Sn Single Crystal to Improve its Thermoelectric Properties

Dislocations have increasingly become important for improving the thermoelectric properties of thermoelectric materials due to their more pronounced scattering effect on phonons than on carriers. This study combined the introduction of the dislocation cores through domain engineering with the generation of Mg vacancies (V_Mg) by controlling point defects to achieve low lattice thermal conductivity and high power factor in n-type and p-type Mg₂Sn single crystals (SCs). The V_Mg domain with ordered atomic arrangements allowed carrier transport with minimal scattering, while the high dislocation density at the interface effectively scattered phonons, thereby decoupling carrier-phonon transport. This resulted in obtaining the peak zT values of 0.83(8) and 0.42(4) for n-type and p-type Mg₂Sn SCs, respectively. The outstanding combination of domain engineering and point defect control techniques could be a strategy for developing high-performance thermoelectric materials.