Rietveld refinement of the crystal structures of Rb2 XSi5O12 (X = Ni, Mn)

نویسندگان

  • Anthony M. T. Bell
  • C. Michael B. Henderson
چکیده

The synthetic leucite silicate framework mineral analogues Rb2 XSi5O12 {X = Ni [dirubidium nickel(II) penta-silicate] and Mn [dirubidium manganese(II) penta-silicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetra-hedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb(+) cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetra-hedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni-O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder.

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عنوان ژورنال:

دوره 72  شماره 

صفحات  -

تاریخ انتشار 2016