EN10.08.18 : Band Structure of the Mg3Sb2-Mg3Bi2 Alloy Composition Investigated with Transport Analysis

5:00 PM–7:00 PM Apr 4, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Kazuki Imasato1 Stephen Kang2 1 Saneyuki Ohno2 1 G. Snyder1

1, Northwestern University, Evanston, Illinois, United States
2, California Institute of Technology, Pasadena, California, United States

The strategy of alloying in the Mg3Sb2-Mg3Bi2 thermoelectric compound has originally been understood mostly as a means to reducing the thermal conductivity. However, it is evident from electronic transport properties that alloying also has a significant impact on the band structure. To fully understand the optimum alloy composition for thermoelectrics, it is necessary to model both the p- and n-type compounds as a function of the Mg3Sb2 vs. Mg3Bi2 composition. We establish a model for the optimum alloy composition and find that the electronic property enhancement accounts for about 50 % of the benefits from alloying. We discuss how the Mg3Sb2-Mg3Bi2 alloying impacts the band structure in terms of the band gap, mass, and convergence, which are the essential features that should be considered for band engineering in this material.