Computational Discovery of Stable and Metastable Inorganic Ternary Oxynitrides

Abhishek Sharan, Stephan Lany

Research output: Contribution to journalArticlepeer-review

24 Scopus Citations

Abstract

Materials design from first principles enables exploration of uncharted chemical spaces. Extensive computational searches have been performed for mixed-cation ternary compounds, but mixed-anion systems are gaining increased interest as well. Central to computational discovery is the crystal structure prediction, where the trade-off between reliance on prototype structures and size limitations of unconstrained sampling has to be navigated. We approach this challenge by letting two complementary structure sampling approaches compete. We use the kinetically limited minimization approach for high-throughput unconstrained crystal structure prediction in smaller cells up to 21 atoms. On the other hand, ternary—and, more generally, multinary—systems often assume structures formed by atomic ordering on a lattice derived from a binary parent structure. Thus, we additionally sample atomic configurations on prototype lattices with cells up to 56 atoms. Using this approach, we searched 65 different charge-balanced oxide-nitride stoichiometries, including six known systems as the control sample. The convex hull analysis is performed both for the thermodynamic limit and for the case of synthesis with activated nitrogen sources. We identified 34 phases that are either on the convex hull or within a viable energy window for potentially metastable phases. We further performed structure sampling for “missing” binary nitrides whose energies are needed for the convex hull analysis. Among these, we discovered metastable Ce3N4 as a nitride analog of the tetravalent cerium oxide, which becomes stable under slightly activated nitrogen condition ΔμN > +0.07 eV. Given the outsize role of CeO2 in research and application, Ce3N4 is a potentially important discovery.

Original languageAmerican English
Article number234706
Number of pages10
JournalThe Journal of Chemical Physics
Volume154
Issue number23
DOIs
StatePublished - 21 Jun 2021

Bibliographical note

Publisher Copyright:
© 2021 Public Domain.

NREL Publication Number

  • NREL/JA-5K00-79525

Keywords

  • atomic structure
  • chemical space
  • computational materials discovery
  • density functional theory
  • high performance computing
  • hybrid density functional calculations
  • oxynitride
  • phase transitions
  • stoichiometry
  • thermodynamic functions
  • thermodynamic limit

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