TY - JOUR

T1 - Preparation, crystal structure and thermal expansion of a novel layered borate, Ba 2Bi 3B 25O 44

AU - Krivovichev, S. V.

AU - Bubnova, R. S.

AU - Volkov, S. N.

AU - Krzhizhanovskaya, M. G.

AU - Egorysheva, A. V.

AU - Filatov, S. K.

PY - 2012/12

Y1 - 2012/12

N2 - 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 °.

AB - 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 °.

KW - Barium and bismuth borate

KW - Crystal structure

KW - Thermal expansion

UR - http://www.scopus.com/inward/record.url?scp=84865710593&partnerID=8YFLogxK

U2 - 10.1016/j.jssc.2012.07.051

DO - 10.1016/j.jssc.2012.07.051

M3 - Article

AN - SCOPUS:84865710593

VL - 196

SP - 11

EP - 16

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

SN - 0022-4596

ER -