A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder

Santanu Roy, Yang Liu, Mehmet Topsakal, Elaine Dias, Ruchi Gakhar, William C. Phillips, James F. Wishart, Denis Leshchev, Phillip Halstenberg, Sheng Dai, Simerjeet K. Gill, Anatoly I. Frenkel, Vyacheslav S. Bryantsev

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

To examine ion solvation, exchange, and speciation for minority components in molten salts (MS) typically found as corrosion products, we propose a multimodal approach combining extended X-ray absorption fine structure (EXAFS) spectroscopy, optical spectroscopy,ab initiomolecular dynamics (AIMD) simulations, and rate theory of ion exchange. Going beyond conventional EXAFS analysis, our method can accurately quantify populations of different coordination states of ions with highly disordered coordination environments via linear combination fitting of the EXAFS spectra of these coordination states computed from AIMD to the experimental EXAFS spectrum. In a case study of dilute Ni(II) dissolved in the ZnCl2+KCl melts, our method reveals heterogeneous distributions of coordination states of Ni(II) that are sensitive to variations in temperature and melt composition. These results are fully explained by the difference in the chloride exchange dynamics at varied temperatures and melt compositions. This insight will enable a better understanding and control of ion solubility and transport in MS.

Original languageEnglish
Pages (from-to)15298-15308
Number of pages11
JournalJournal of the American Chemical Society
Volume143
Issue number37
DOIs
StatePublished - Sep 22 2021

Funding

This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science. BNL, INL, and ORNL are operated under DOE contracts DE-SC0012704, DE-AC07-05ID14517, and DE-AC05-00OR22725, respectively. This research used resources of the ISS (8-ID) beamline at the National Synchrotron Light Source II operated by the Brookhaven National Laboratory under Contract No. DE-SC0012704, a U.S. Department of Energy (DOE), Office of Science User Facility. This research used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory and the National Energy Research Scientific Computing Center (NERSC), which are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725 and No. DE-AC02-05CH11231, respectively.

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