The Electronic Transport Channel Protection and Tuning in Real Space to Boost the Thermoelectric Performance of Mg3+δSb2-yBiy near Room Temperature
(a) Crystalline structure of Mg3Sb2 with Mn at the interstitial site. (b) Charge density in (011) plane. (c) The square of real-space wave function (i.e., the “charge” density) at CBM along Mg1-Mg2 line for Mg3Sb2 bulk (black solid line), under 4% strain (red solid line) along the -axis and the difference (black dotted line) between “charge” density of Mg3Sb2 under 4% strain and bulk. Clear reduction of the covalence-like overlap of Mg1 and Mg2 3s orbitals between Mg1 and Mg2 is shown with the strain and the released “charge” mostly goes to Mg1. (d) Strain-dependent effective mass at conduction band edge. The inset compares the calculated charge density distribution of the two cases in the a-b cross section at the -axis fractional coordinate , with the same setting of isosurface around 15% of the maximum values.