Jahn–Teller Driven Electronic Instability in Thermoelectric Tetrahedrite

Sebastian O. Long, Anthony V. Powell, Stephen Hull, Fabio Orlandi, Chiu C. Tang, Andrew R. Supka, Marco Fornari, Paz Vaqueiro

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Tetrahedrite, Cu12Sb4S13, is an abundant mineral with excellent thermoelectric properties owing to its low thermal conductivity. The electronic and structural origin of the intriguing physical properties of tetrahedrite, including its metal-to-semiconductor transition (MST), remains largely unknown. This work presents the first determination of the low-temperature structure of tetrahedrite that accounts for its unique properties. Contrary to prior conjectures, the results show that the trigonal–planar copper cations remain in planar coordination below the MST. The atomic displacement parameters of the trigonal–planar copper cations, which have been linked to low thermal conductivity, increase by 200% above the MST. The phase transition is a consequence of the orbital degeneracy of the highest occupied 3d cluster orbitals of the copper clusters found in the cubic phase. This study reveals that a Jahn–Teller electronic instability leads to the formation of “molecular-like” Cu5 7+ clusters and suppresses copper rattling vibrations due to the strengthening of direct copper–copper interactions. First principles calculations demonstrate that the structural phase transition opens a small band gap in the electronic density of states and eliminates the unstable phonon modes. These results provide insights on the interplay between phonon transport, electronic properties, and crystal structure in mixed-valence compounds.

Original languageEnglish
Article number1909409
JournalAdvanced Functional Materials
Volume30
Issue number12
DOIs
StatePublished - Mar 1 2020

Keywords

  • Jahn–Teller
  • charge ordering
  • metal–insulator transition
  • thermal conductivity
  • thermoelectric

Fingerprint

Dive into the research topics of 'Jahn–Teller Driven Electronic Instability in Thermoelectric Tetrahedrite'. Together they form a unique fingerprint.

Cite this