Synthesis and X-ray characterization of silicon clathrates

Ganesh K. Ramachandran, Jianjun Dong, Jason Diefenbacher, Jan Gryko, Robert F. Marzke, Otto F. Sankey, Paul F. McMillan

Research output: Contribution to journalArticlepeer-review

130 Scopus citations


We report on the synthesis and characterization of two silicon clathrates, Na8Si46 and NaxSi136(x = 4-23), by powder X-ray diffraction, combined with Rietveld profile analysis. In Na8Si46, no deviation from the ideal stoichiometry is observed. In NaxSi136, systematic changes in X-ray diffraction intensities enable the Na content and site occupancy to be characterized. In the same structure, we observe a ∼0.5% increase in the unit cell edge upon progressing from Na4Si136 to Na23Si136. A statistical mechanical model, combined with experimental data for this phase reveals a preference for the removal of sodium from the smaller of the two available cages by 0.190 ± 0.050 eV.

Original languageEnglish (US)
Pages (from-to)716-730
Number of pages15
JournalJournal of Solid State Chemistry
Issue number2
StatePublished - Jul 1999

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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