Bonding Hierarchy Gives Rise to High Thermoelectric Performance in Layered Zintl Compound BaAu2P4

Koushik Pal, Jiangang He, C. Wolverton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The search for new thermoelectric materials has gained rapid progress in recent years as thermoelectric technology offers the potential for environmentally friendly and sustainable energy conversion methods from waste heat to electricity. In this work, we use first-principles calculations based on density functional theory to predict high thermoelectric performance in BaAu2P4, a layered Zintl compound with a small band gap. BaAu2P4 exhibits crystallographic heterogeneity in which rigid [Au2P4]2- units are separated by layers of Ba2+ cations, which are bonded relatively weakly to the lattice through electrostatic interactions. The phosphorus atoms are covalently bonded to each other and form infinite chains within the crystal. While the phosphorus chains facilitate large electrical conductivity, the presence of multiple bands near the Fermi level gives rise to an enhanced Seebeck coefficient. On the other hand, the loosely bound Ba along with Au strongly scatter the heat carrying acoustic phonons, significantly reducing the lattice thermal conduction along the stacking direction. As a consequence of this bonding hierarchy (i.e., coexisting rigid and fluctuating sublattices), BaAu2P4 exhibits a large power factor and low lattice thermal conductivity, which results in a high thermoelectric figure of merit (zT). Thus, our findings should encourage the exploration of new thermoelectric materials in the family of layered compounds with small band gaps and crystallographic heterogeneity.

Original languageEnglish (US)
Pages (from-to)7760-7768
Number of pages9
JournalChemistry of Materials
Volume30
Issue number21
DOIs
StatePublished - Nov 13 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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