Dynamics of molten alkali halides: LiCl and DCl

L. Pusztai, R. L. McGreevy

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The authors have measured the inelastic neutron scattering spectra of three samples of molten 7LiCl with different isotopic chlorine compositions, and of one sample of molten KCl, using the time-of-flight spectrometer IN6 at the Institut Laue-Langevin. It is observed that the main peak in the total dynamical structure factor for LiCl is sharply peaked in both Q and omega directions, while that for KCl is much weaker and broader. The spectra for LiCl show evidence for two types of collective mode with characteristic energies of 10-20 and 40-50 meV. Using the differences between the samples, it is possible to show that appropriate pairs of dynamical variables for these modes are m+, -m- (low energies) and q+, -q- (high energies), whereas in molten CsCl the variables have been shown to be m+, m- and q+, q-. They propose that for the alkali chlorides (where the ionic radius ratio r+/r-<1) the former variables are appropriate when m+<m-, and the latter when m +>m-. There is a crossover between the variables, resulting in strong-mode coupling, when m+=m-. The data for KCl are consistent with this proposition.

Original languageEnglish
Article number010
Pages (from-to)2369-2380
Number of pages12
JournalJournal of Physics: Condensed Matter
Issue number13
Publication statusPublished - Dec 1 1989


ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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