Scientific Reports (May 2017)

Ag-Mg antisite defect induced high thermoelectric performance of α-MgAgSb

  • Zhenzhen Feng,
  • Jihua Zhang,
  • Yuli Yan,
  • Guangbiao Zhang,
  • Chao Wang,
  • Chengxiao Peng,
  • Fengzhu Ren,
  • Yuanxu Wang,
  • Zhenxiang Cheng

DOI
https://doi.org/10.1038/s41598-017-02808-8
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 12

Abstract

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Abstract Engineering atomic-scale native point defects has become an attractive strategy to improve the performance of thermoelectric materials. Here, we theoretically predict that Ag-Mg antisite defects as shallow acceptors can be more stable than other intrinsic defects under Mg-poor‒Ag/Sb-rich conditions. Under more Mg-rich conditions, Ag vacancy dominates the intrinsic defects. The p-type conduction behavior of experimentally synthesized α-MgAgSb mainly comes from Ag vacancies and Ag antisites (Ag on Mg sites), which act as shallow acceptors. Ag-Mg antisite defects significantly increase the thermoelectric performance of α-MgAgSb by increasing the number of band valleys near the Fermi level. For Li-doped α-MgAgSb, under more Mg-rich conditions, Li will substitute on Ag sites rather than on Mg sites and may achieve high thermoelectric performance. A secondary valence band is revealed in α-MgAgSb with 14 conducting carrier pockets.