Synthesis and spectroscopic characterization of P-doped Na 4Si4

Jialing Wang, Sabyasachi Sen, Ping Yu, Nigel D. Browning, Susan M. Kauzlarich

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8 Scopus citations


Na4Si4 is a Zintl salt composed of Na+ cations and Si44- tetrahedral anions and is a unique solid-state precursor to clathrate structures and nanomaterials. In order to provide opportunities for the synthesis of complex materials, phosphorus was explored as a possible substituent for silicon. Phosphorus doped sodium silicides Na4Si 4-xPx (x≤0.04) were prepared by reaction of Na with the mechanically alloyed Si4-x:Px (x=0.04, 0.08, 0.12) mixture in a sealed Nb tube at 650 °C for 3 days. Energy dispersive X-ray spectroscopy confirms the presence of P in all products. Powder X-ray diffraction patterns are consistent with the retention of the Na 4Si4 crystal structure. As the amount of P increases, a new peak in the diffraction pattern that can be assigned to black phosphorus is apparent above the background. Raman and solid-state NMR provide information on phosphorus substitution in the Na4Si4 structure. Raman spectroscopy shows a shift of the most intense band assigned to the Si44- ν1 (A1) mode from 486.4 to 484.0 cm-1 with increasing P, consistent with P replacement of Si. Differential nuclear spin-lattice relaxation for the Si sites determined via 29Si solid-state NMR provides direct evidence for SiP bonding in the (Si 1-xPx)4- tetrahedron. The 23Na NMR shows additional Na...P interactions and the 31P NMR shows two P sites, consistent with P presence in both of the crystallographic sites in the (Si4)4- tetrahedron.

Original languageEnglish (US)
Pages (from-to)2522-2527
Number of pages6
JournalJournal of Solid State Chemistry
Issue number11
StatePublished - Nov 2010


  • Clathrate
  • Metal silicide
  • Raman spectroscopy
  • Solid-state multinuclear NMR
  • Zintl phase

ASJC Scopus subject areas

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


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