Preparation, crystal structure and thermal expansion of a novel layered borate, Ba 2Bi 3B 25O 44

S. V. Krivovichev, R. S. Bubnova, S. N. Volkov, M. G. Krzhizhanovskaya, A. V. Egorysheva, S. K. Filatov

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Single crystals of a new compound, Ba 2Bi 3B 25O 44, were grown by cooling a melt of non-stoichiometric composition. The crystal structure was solved by direct methods and refined to R=0.030 (wR=0.090). The compound is trigonal, R3̄ m, a=7.851(2), c=46.20(1) Å, V=2466.6(6) Å 3, Z=3. The structure is based upon a borate layered anion of the type not previously observed in inorganic compounds. The layer consists of three sublayers; it is ∼13 Å thick and oriented parallel to (001). Two of the sublayers are built from triborate groups, [B 3O 8] 7-, whereas the central sublayer consists of triborate groups, [B 3O 6] 3-. The interlayer space is occupied by the Bi 3 ions in octahedral coordination. The Ba 2 cations are located in the cavities within borate layer. The single-phase polycrystalline sample of Ba 2Bi 3B 25O 44 prepared by solid-state reactions from a stoichiometric mixture has been investigated by high-temperature X-ray powder diffraction in air. Anisotropic character of the thermal expansion is not typical for layered structures: α a=12, α c=6, α V=30×10 -6 ° -1 at 25 °; anisotropy increases on heating: α a=12, α c=0, α V=24×10 -6 ° -1 at 700 °.

Original languageEnglish
Pages (from-to)11-16
Number of pages6
JournalJournal of Solid State Chemistry
StatePublished - Dec 2012

Scopus subject areas

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


  • Barium and bismuth borate
  • Crystal structure
  • Thermal expansion


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