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Understanding the Band Engineering in Mg 2 Si‐Based Systems from Wannier‐Orbital Analysis
Author(s) -
Tan Xiaojian,
Yin Yig,
Hu Haoyang,
Xiao Yukun,
Guo Zhe,
Zhang Qiang,
Wang Hongxiang,
Liu GuoQiang,
Jiang Jun
Publication year - 2020
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.201900543
Subject(s) - electronic band structure , wannier function , convergence (economics) , conduction band , materials science , electronic structure , band gap , condensed matter physics , dopant , semimetal , chemical bond , lattice (music) , thermoelectric effect , doping , physics , chemical physics , thermodynamics , quantum mechanics , acoustics , economics , economic growth , electron
The Mg 2 Si1 − x Sn x solid solution is one of the most representative examples of band engineering, in which the thermoelectric performance is significantly improved by the conduction band convergence. The mechanism behind it is simply explained by the chemical differences between Si and Sn. Here a systematically theoretical study is reported based on Wannier function analysis. It is revealed that the band convergence in Mg 2 Si1 − x Sn x is actually driven by the variation of lattice constant, since the heavy and light conduction valleys have different dependence on the bonding length. Alternatively, the band engineering can also be achieved by introducing cation dopants to tune the relative strength of the two chemical bonds directly. In Mg2 − x Sr x Si, a similar band convergence to Mg 2 Si1 − x Sn x is predicted by the band structure calculations. This work provides an insightful understanding of the band convergence in Mg 2 Si‐based materials, and it enables a more efficient and plentiful design for experimental studies.