The crystal structures of CeSiO4 and Ca2Ce8(SiO4)(6)O-2

J M S Skakle, C L Dickson, F P Glasser

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Abstract

Two new solubility-limiting phases relevant to nuclear waste disposal are reported, namely CeSiO4 and Ca2Ce8(SiO4)O-2, produced by hydrothermal synthesis at 180 degreesC. X-ray diffraction data are presented for both compounds. Rietveld refinement was performed for each of these phases. CeSiO4 was confirmed to be a zircon structure type, with space group 14(1)/amd, unit cell a=6.9564(3), c= 6.1953(4) Angstrom. Bond lengths for SiO4 are in excellent agreement with published values; Ce4+ is coordinated to eight oxygen atoms with four regular and four short bonds. Ca2Ce8(SiO4)O-2 was shown to have an apatite structure, with space group P6(3)/m and unit cell a=9.4343(3), c = 6.8885(4) Angstrom. The unit cell and bond lengths were found to be slightly smaller than would be expected from other lanthanide-containing analogs; possible reasons for this are discussed. (C) 2000 International Centre for Diffraction Data. [S0885-7156(00)00103-2].

Original languageEnglish
Pages (from-to)234-238
Number of pages5
JournalPowder Diffraction
Volume15
Publication statusPublished - 2000

Keywords

  • Rietveld refinement
  • powder diffraction
  • actinide simulants
  • cement nuclear waste disposal
  • NEUTRON POWDER DIFFRACTION
  • BOND LENGTHS
  • ZIRCON

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