Complex Structure of Molten NaCl-CrCl3Salt: Cr-Cl Octahedral Network and Intermediate-Range Order

Qing Jie Li, David Sprouster, Guiqiu Zheng, Jörg C. Neuefeind, Alexander D. Braatz, Joanna McFarlane, Daniel Olds, Stephen Lam, Ju Li, Boris Khaykovich

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The resurgence of the molten-salt nuclear reactors (MSRs) creates interesting problems in molten-salt chemistry. As MSRs operate, the composition and physical properties of salts change because of fission and corrosion. Since Cr is the principal corrosion product and NaCl is a common constituent, we studied the atomic structure of molten NaCl-CrCl3. We found networks of CrCl63- octahedra and an intermediate-range order with a nonmonotonic temperature behavior with a remarkable agreement between measurements and ab initio simulations. Even though the corrosion results in minute quantities of dissolved Cr, the speciation of Cr could lead to changes in molten-salt properties in nuclear and solar salts. In particular, we found a much lower melting temperature than expected and a broad metastable liquid-solid coexistence phase. The availability of Cr isotopes with very different neutron scattering properties makes Cr an ideal model multivalent ion for experimental validation of new atomistic models such as neural network interatomic potentials.

Original languageEnglish
Pages (from-to)3044-3056
Number of pages13
JournalACS Applied Energy Materials
Volume4
Issue number4
DOIs
StatePublished - Apr 26 2021

Funding

We acknowledge multiple useful discussions with Richard Mayes, Stephen Raiman, Jake McMurray (ORNL), and Raluca Scarlat (UC Berkeley). We acknowledge the help of Abbey McAllister (ORNL) with sample handling and preparation. This material is based upon work supported by the Department of Energy under Award Number DE-NE0008751. This research used resources at the Spallation Neutron Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated by the Oak Ridge National Laboratory, and the beamline 28-ID-1 (PDF) of the National Synchrotron Light Source II, a DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. This work also used the Extreme Science and Engineering Discovery Environment (XSEDE) resources at the Texas Advanced Computing Center (TACC) through allocation DMR190055.

Keywords

  • chromium chloride
  • melting
  • molten salt
  • pair distribution function
  • phase diagram
  • prepeak
  • sodium chloride

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