A new borosilicate feldspar, KBSi3O8: Synthesis, crystal structure and thermal behavior

M.G. Krzhizhanovskaya, R.S. Bubnova, W. Depmeier, N.S. Rahmoun, S.K. Filatov, V.L. Ugolkov

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Single crystals of the new borosilicate feldspar with nominal composition KBSi3O8 were grown hydrothermally. The crystal structure of KBSi3O8 was determined by direct methods: it is monoclinic, C2/m, a=8.4377(8), b=12.4152(11), c=6.8769(7) Å, β = 116.133(7)°, V = 646.75(11) Å3, dcalc = 2.693 g/cm3. The structure corresponds to that of monoclinic aluminosilicate feldspar with differences only in the size and density of the tetrahedral framework due to the presence of boron instead of aluminium. The distribution of Si and B over the tetrahedral sites is partially ordered with one Si-rich tetrahedron ( = 1.60 Å), and another one occupied by Si and B in almost equal proportion ( = 1.55 Å). According to the high temperature X-ray diffraction study the expansion of the structure is highly anisotropic: α1 = 21, α2 = 2, α3 = 5 × 10–6 K–1, ∠(α3c) = 7°. The direction of maximal expansion approximately coincides with the short diagonal of the ac parallelogram. KBSi3O8 obtained by hydrothermal synthesis is
Original languageEnglish
Pages (from-to)446-451
Number of pages6
JournalZeitschrift fur Kristallographie
Volume227
Issue number7
StatePublished - 2012

Keywords

  • Single crystal X-ray diffraction
  • Hydrothermal synthesis
  • Thermal expansion
  • Feldspar
  • Borosilicate

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