Synthesis, crystal structure and infrared spectroscopy of a new non-centrosymmetric mixed-anion phosphate Na4Mg3(PO4)2(P2O7)

Rachid Essehli, Brahim El Bali, Said Benmokhtar, Hartmut Fuess, Ingrid Svoboda, Said Obbade

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The new mixed-anion phosphate Na4Mg3(PO4)2(P2O7) has been prepared and its structure has been determined by single crystal X-ray diffraction. The crystal structure was refined to R = 0.0290 (wR = 0.0836) for 1527 independent reflexions. This compound crystallizes in the orthorhombic non-centrosymmetric space group Pn21a with a = 17.985(2) Å, b = 6.525(9) Å, c = 10.511(1) Å, and Z = 4. The framework is built up from [PO4] tetrahedra, [P2O7] groups and [MgO6] octahedra. The three dimensional structure consists of [Mg3P2O13] infinite layers parallel to the bc plane. The layers are built up from [MgO6] octahedra and [PO4] tetrahedral, they are connected along the a axis by O-P-O-P-O bridges of the diphosphate groups. Large tunnels extending along the three main crystallographic directions host four crystallographically distinct sodium cations. The infrared spectrum of Na4Mg3(PO4)2(P2O7) is interpreted on the basis of P2O74- and PO43- vibrations. The appearance of νsP-O-P in the spectrum suggests a bent P-O-P bridge for the P2O74- ions in the compound, which is in agreement with the X-ray data.

Original languageEnglish
Pages (from-to)654-660
Number of pages7
JournalJournal of Alloys and Compounds
Issue number1-2
Publication statusPublished - 18 Mar 2010



  • Crystal structure
  • Infrared
  • Mixed anions phosphate
  • X-rays

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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