Abstract
In order to clarify the doping influence of different donor dopants (Co, Mn, and Te) in Mg3Sb1.5Bi0.5 crystals, defect formation energy and electronic structures are successfully determined by first-principles calculations. Also, its effect on thermoelectric properties parameters is analyzed using the crystals prepared via the directional solidification method. It is determined that Co atoms substitute Mg2 sites, while Mn atoms are more likely to be doped at interstitial sites. Both Sb and Bi sites are susceptible to the substitution of Te atom. Te- and Co-doped crystals can achieve higher carrier concentration and carrier effective mass, respectively. Moreover, interstitial Mn atoms render a balanced influence on carrier concentration and carrier effective mass, resulting in an optimal electronic transport performance. The maximum of PF is 2.31 W m-1K−2, which is comparable to the previously reported codoped Mg3Sb1.5Bi0.5 crystals. A theoretical reference is presented to further optimize the properties of Mg3Sb1.5Bi0.5 crystals.
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