Complete Description of the LaCl 3 -NaCl Melt Structure and the Concept of a Spacer Salt That Causes Structural Heterogeneity.

Autor: Emerson MS; Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States., Sharma S; Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States., Roy S; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States., Bryantsev VS; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States., Ivanov AS; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States., Gakhar R; Pyrochemistry and Molten Salt Systems Department, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States., Woods ME; Pyrochemistry and Molten Salt Systems Department, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States., Gallington LC; X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Lemont, Illinois 60439, United States., Dai S; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.; Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States., Maltsev DS; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States., Margulis CJ; Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States.
Jazyk: angličtina
Zdroj: Journal of the American Chemical Society [J Am Chem Soc] 2022 Nov 30; Vol. 144 (47), pp. 21751-21762. Date of Electronic Publication: 2022 Nov 15.
DOI: 10.1021/jacs.2c09987
Abstrakt: Lanthanides are important fission products in molten salt reactors, and understanding their structure and that of their mixtures is relevant to many scientific and technological problems including the recovery and separation of rare earth elements using molten salt electrolysis. The literature on molten salts and specifically on LaCl 3 and LaCl 3 -NaCl mixtures is often fragmented, with different experiments and simulations coinciding in their explanation for certain structural results but contradicting or questioning for others. Given the very practical importance that actinide and lanthanide salts have for energy applications, it is imperative to arrive at a clear unified picture of their local and intermediate-range structure in the neat molten state and when mixed with other salts. This article aims to unequivocally answer a set of specific questions: is it correct to think of long-lived octahedral coordination structures for La 3+ ? What is the nature as a function of temperature of networks and intermediate-range order particularly upon dilution of the trivalent ion salt? Is the so-called scattering first sharp diffraction peak (FSDP) for neat LaCl 3 truly indicative of intermediate-range order? If so, why is there a new lower- q peak when mixed with NaCl? Are X-ray scattering and Raman spectroscopy results fully consistent and easily described by simulation results? We will show that answers to these questions require that we abandon the idea of a most prominent coordination state for M 3+ ions and instead think of multiple competing coordination states in exchange due to significant thermal energy in the molten state.
Databáze: MEDLINE
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