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

Santanu RoyShobha SharmaWaruni V KarunaratneFei WuRuchi GakharDmitry S MaltsevPhillip W HalstenbergMilinda AbeykoonSimerjeet K GillYuanpeng ZhangShannon Mark MahurinSheng DaiVyacheslav S BryantsevClaudio J MargulisAleksandr S Ivanov
Published in: Chemical science (2021)
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.
Keyphrases
  • high temperature
  • molecular dynamics simulations
  • quantum dots
  • high resolution
  • single cell
  • ionic liquid
  • rna seq
  • magnetic resonance
  • aqueous solution
  • magnetic resonance imaging
  • mass spectrometry
  • electron microscopy