X-ray scattering reveals ion clustering of dilute chromium species in molten chloride medium

Santanu Roy; Shobha Sharma; Waruni V Karunaratne; Fei Wu; Ruchi Gakhar; Dmitry S Maltsev; Phillip Halstenberg; Milinda Abeykoon; Simerjeet K Gill; Yuanpeng Zhang; Shannon M Mahurin; Sheng Dai; Vyacheslav S Bryantsev; Claudio J Margulis; Alexander S Ivanov

doi:10.1039/D1SC01224J

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X-ray scattering reveals ion clustering of dilute chromium species in molten chloride medium

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X-ray scattering reveals ion clustering of dilute chromium species in molten chloride medium

Santanu Roy, Shobha Sharma, Waruni V Karunaratne, Fei Wu, Ruchi Gakhar, Dmitry S Maltsev, Phillip Halstenberg, Milinda Abeykoon, Simerjeet K Gill, Yuanpeng Zhang, …

Chemical science (Cambridge), Vol.12(23), pp.8026-8035

06/16/2021

DOI: 10.1039/D1SC01224J

PMCID: PMC8208131

PMID: 34194692

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Abstract

Enhancing the solar energy storage and power delivery afforded by emerging molten salt-based technologies requires a fundamental understanding of the complex interplay between structure and dynamics of the ions in the high-temperature media. Here we report results from a comprehensive study integrating synchrotron X-ray scattering experiments, ab initio molecular dynamics simulations and rate theory concepts to investigate the behavior of dilute Cr3+ metal ions in a molten KCl–MgCl2 salt. Our analysis of experimental results assisted by a hybrid transition state-Marcus theory model reveals unexpected clustering of chromium species leading to the formation of persistent octahedral Cr–Cr dimers in the high-temperature low Cr3+ concentration melt. Furthermore, our integrated approach shows that dynamical processes in the molten salt system are primarily governed by the charge density of the constituent ions, with Cr3+ exhibiting the slowest short-time dynamics. These findings challenge several assumptions regarding specific ionic interactions and transport in molten salts, where aggregation of dilute species is not statistically expected, particularly at high temperature.

Details

Title: Subtitle: X-ray scattering reveals ion clustering of dilute chromium species in molten chloride medium
Creators: Santanu Roy - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA
Shobha Sharma - Department of Chemistry, The University of Iowa, USA
Waruni V Karunaratne - Department of Chemistry, The University of Iowa, USA
Fei Wu - Department of Chemistry, The University of Iowa, USA
Ruchi Gakhar - Pyrochemistry and Molten Salt Systems Department, Idaho National Laboratory, Idaho Falls, USA
Dmitry S Maltsev - Department of Chemistry, University of Tennessee, Knoxville, USA
Phillip Halstenberg - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA, Department of Chemistry
Milinda Abeykoon - National Synchrotron Light Source II (NSLS-II), Brookhaven National Lab, USA
Simerjeet K Gill - Chemistry Division, Brookhaven National Lab, Upton, USA
Yuanpeng Zhang - Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, USA
Shannon M Mahurin - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA
Sheng Dai - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA, Department of Chemistry
Vyacheslav S Bryantsev - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA
Claudio J Margulis - Department of Chemistry, The University of Iowa, USA
Alexander S Ivanov - Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, USA
Resource Type: Journal article
Publication Details: Chemical science (Cambridge), Vol.12(23), pp.8026-8035
DOI: 10.1039/D1SC01224J
PMID: 34194692
PMCID: PMC8208131
NLM abbreviation: Chem Sci
ISSN: 2041-6520
eISSN: 2041-6539
Grant note: DOI: 10.13039/100000015, name: U.S. Department of Energy, award: DE-SC0012704, DE-AC05-00OR22725
Language: English
Date published: 06/16/2021
Academic Unit: Chemistry
Record Identifier: 9984217452402771

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