Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Ab Initio Molecular Dynamics

Santanu Roy; Martin Brehm; Shobha Sharma; Fei Wu; Dmitry S Maltsev; Phillip Halstenberg; Leighanne C Gallington; Shannon M Mahurin; Sheng Dai; Alexander S Ivanov; Claudio J Margulis; Vyacheslav S Bryantsev

doi:10.1021/acs.jpcb.1c03786

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Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Ab Initio Molecular Dynamics

Journal article

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Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Ab Initio Molecular Dynamics

Santanu Roy, Martin Brehm, Shobha Sharma, Fei Wu, Dmitry S Maltsev, Phillip Halstenberg, Leighanne C Gallington, Shannon M Mahurin, Sheng Dai, Alexander S Ivanov, …

The journal of physical chemistry. B, Vol.125(22), pp.5971-5982

06/10/2021

DOI: 10.1021/acs.jpcb.1c03786

PMID: 34037400

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https://www.osti.gov/biblio/1817517View

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Abstract

In this work, we resolve a long-standing issue concerning the local structure of molten MgCl2 by employing a multimodal approach, including X-ray scattering and Raman spectroscopy, along with the theoretical modeling of the experimental spectra based on ab initio molecular dynamics (AIMD) simulations utilizing several density functional theory (DFT) methods. We demonstrate the reliability of AIMD simulations in achieving excellent agreement between the experimental and simulated spectra for MgCl2 and 50 mol % MgCl2 + 50 mol % KCl, and ZnCl2, thus allowing structural insights not directly available from experiment alone. A thorough computational analysis using five DFT methods provides a convergent view that octahedrally coordinated magnesium in pure MgCl2 upon melting preferentially coordinates with five chloride anions to form distorted square pyramidal polyhedra that are connected via corners and to a lesser degree via edges. This is contrasted with the results for ZnCl2, which does not change its tetrahedral coordination on melting. Although the five-coordinate MgCl53– complex was not considered in the early literature, together with an increasing tendency to form a tetrahedrally coordinated complex with decreasing the MgCl2 content in the mixture with alkali metal chloride systems, current work reconciles the results of most previous seemingly contradictory experimental studies.

B: Liquids; Chemical and Dynamical Processes in Solution

Details

Title: Subtitle: Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Ab Initio Molecular Dynamics
Creators: Santanu Roy - Chemical Sciences Division
Martin Brehm - Institut für Chemie
Shobha Sharma - Department of Chemistry
Fei Wu - Department of Chemistry
Dmitry S Maltsev - Department of Chemistry
Phillip Halstenberg - Department of Chemistry
Leighanne C Gallington - X-ray Science Division, Advanced Photon Source
Shannon M Mahurin - Chemical Sciences Division
Sheng Dai - Department of Chemistry
Alexander S Ivanov - Chemical Sciences Division
Claudio J Margulis - Department of Chemistry
Vyacheslav S Bryantsev - Chemical Sciences Division
Resource Type: Journal article
Publication Details: The journal of physical chemistry. B, Vol.125(22), pp.5971-5982
DOI: 10.1021/acs.jpcb.1c03786
PMID: 34037400
NLM abbreviation: J Phys Chem B
ISSN: 1520-6106
eISSN: 1520-5207
Publisher: American Chemical Society
Grant note: name: US Department of Energy, award: DEAC05-00OR22725
Language: English
Date published: 06/10/2021
Academic Unit: Chemistry
Record Identifier: 9984216690802771

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