A Two-Dimensional Type I Superionic Conductor

Alexander J.E. Rettie*, Jingxuan Ding, Michael J. Johnson, Christos D. Malliakas, Naresh C. Osti, Duck Young Chung, Raymond Osborn, Olivier Delaire, Stephan Rosenkranz, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Superionic conductors (SICs) possess liquid-like ionic diffusivity in the solid state, finding wide applicability from electrolytes in energy storage to materials for thermoelectric energy conversion. Type I SICs (e.g., AgI, Ag2Se, etc.) are defined by an abrupt transition to the superionic state and have so far been found exclusively in three-dimensional crystal structures. Here, we reveal a two-dimensional type I SIC, a-KAg3Se2 by scattering techniques and complementary simulations. Quasielastic neutron scattering and ab initio molecular dynamics simulations confirm that the superionic Ag+ ions are confined to sub-nanometre sheets, with the simulated local structure validated by experimental X-ray powder pair-distribution-function analysis. Finally, we demonstrate that the phase transition temperature can be controlled by chemical substitution of the alkali metal ions that comprise the immobile charge-balancing layers. Our work thus extends the known classes of SICs and will facilitate the design of new materials with tailored ionic conductivities and phase transitions.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Aug 24 2020

ASJC Scopus subject areas

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

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