Incorporation of indium into the Zn13Sb10 thermoelectric material

The composition of the In-substituted Zn13Sb10 phases follows the Zn13-1.5xInxSb10 charge-balanced formula and the reduction in the Zn content is due to the In3+ oxidation state, compared to the Zn2+ oxidation state. Zn deficiency in the In-doped samples is supported by the X-ray powder diffraction and EDS elemental analyses. Single-crystal X-ray diffraction refinement backs the Zn deficiency by revealing absence of Zn atoms in the interstitial sites and decreased occupancy of the main Zn site. The heat capacity measurements indicate that incorporation of In suppresses the α → α′ (235 K) and α′ → β (254 K) phase transitions, which could be due to the disappearance of some interstitial Zn atoms and/or difficulty in ordering the remaining ones. Both electrical resistivity and Seebeck coefficient data suggest a decrease in charge carrier concentration, stemming from an increased occupancy of the valence band. The thermal conductivity reveals changes in the phonon scattering pathways upon In doping; dominance of point defect scattering in Zn13-1.5xInxSb10 vs. Umklapp scattering in the pristine Zn13Sb10.