Investigation of n-Type Doping Strategies for Mg3Sb2

Prashun Gorai, Eric Toberer, Vladan Stevanovic, Brenden Ortiz

Research output: Contribution to journalArticlepeer-review

82 Scopus Citations

Abstract

Recent, and somewhat surprising, successful n-type doping of Mg3Sb2 was the key to realizing high thermoelectric performance in this material. Herein, we use first-principles defect calculations to investigate different extrinsic n-type doping strategies for Mg3Sb2 and to reveal general chemical trends in terms of dopant solubilities and maximal achievable electron concentrations. In agreement with experiments, we find that Sb substitution is an effective doping strategy, with Se and Te doping predicted to yield up to ~8 x 1019 cm-3 electrons. However, we also find that Mg substitution with trivalent (or higher) cations can be even more effective; in particular, the predicted highest achievable electron concentration (~5 x 1020 cm-3) with La as an extrinsic dopant exceeds that of Se and Te doping. Interstitial doping (Li, Zn, Cu, Be) is found to be largely ineffective either due to self-compensation (Li) or high formation energy (Zn, Cu, Be). Our results offer La as an alternative dopant to Te and Se and reinforce the need for careful phase boundary mapping in achieving high electron concentrations in Mg3Sb2.
Original languageAmerican English
Pages (from-to)13806-13815
Number of pages10
JournalJournal of Materials Chemistry A
Volume6
Issue number28
DOIs
StatePublished - 2018

NREL Publication Number

  • NREL/JA-5K00-72221

Keywords

  • defect calculations
  • dopant solubility
  • electron concentration
  • formation energies
  • general chemicals
  • high electron concentration
  • self compensation
  • thermoelectric performance

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