Vacancy defect control of colossal thermopower in FeSb2

Iron diantimonide is a material with the highest known thermoelectric power. By combining scanning transmission electron microscopic study with electronic transport neutron, X-ray scattering, and first principle calculation, we identify atomic defects that control colossal thermopower magnitude and nanoprecipitate clusters with Sb vacancy ordering, which induce additional phonon scattering and substantially reduce thermal conductivity. Defects are found to cause rather weak but important monoclinic distortion of the unit cell Pnnm -> Pm. The absence of Sb along [010] for high defect concentration forms conducting path due to Fe d orbital overlap. The connection between atomic defect anisotropy and colossal thermopower in FeSb2 paves the way for the understanding and tailoring of giant thermopower in related materials.

Automated summary

The study identified atomic defects and nanoprecipitate clusters in iron diantimonide that control the thermoelectric power magnitude and thermal conductivity. The connection between atomic defect anisotropy and colossal thermopower in FeSb2 provides insights for understanding and tailoring giant thermopower in related materials.