title: Batisite, Na2BaTi2(Si4O12)O2, from Inagli massif, Aldan, Russia: crystal-structure refinement and high-temperature X-ray diffraction study
metadata.name: dc.date.accessioned
metadata.value: 2020-09-09T07:32:57Z
metadata.lang: -
metadata.name: dc.date.available
metadata.value: 2020-09-09T07:32:57Z
metadata.lang: -
metadata.name: dc.date.issued
metadata.value: 2017
metadata.lang: -
metadata.name: dc.identifier.uri
metadata.value: http://hdl.handle.net/11701/19309
metadata.lang: -
metadata.name: dc.description.abstract
metadata.value: The crystal structure of batisite, Na2BaTi2
  (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia)
  was refined to R1 = 0.032 for 1449 unique observed reflections.
  The mineral is orthorhombic, Imma, a = 8.0921(5),
  b = 10.4751(7), c = 13.9054(9) Å, V = 1178.70(13) Å3. The
  mineral is based upon three-dimensional titanosilicate framework
  consisting of chains of corner-sharing MO6 octahedra
  (M = Ti, Nb, Fe and Zr) and vierer chains of corner-sharing
  SiO4 tetrahedra. Both chains are parallel to the a axis and are
  linked by sharing peripheral O atoms. The octahedral chains
  display disorder ofM atoms and bridging O sites related to the
  out-of-center distortion of octahedral geometry around Ti4+
  cations. Electron microprobe analysis gives SiO2 39.46,
  TiO2 24.66, BaO 21.64, Na2O 7.56, K2O 4.38, Fe2O3 0.90,
  ZrO2 0.66, Nb2O5 0.36, (H2O)calc 0.58, sum 99.76 wt%. The
  seven strongest X-ray powder-diffraction lines [listed as d in
  Å (I) hkl] are: 8.39 (94) 011, 3.386 (56) 031, 3.191 (36) 123,
  2.910 (46) 222, 2.896 (100) 024, 2.175 (45) 035, 1.673 (57)
  055. The thermal behaviour of batisite in the temperature
  range from 25 to 950 °C was studied using high-temperature
  powder X-ray diffraction. The thermal expansion coefficients
  along the principal crystallographic axes are: αa = 14.4× 10−6,
  αb = 8.7 × 10−6, αc = 8.4 × 10−6, αV = 31.5 °C−1 for the
  temperature range 25–500 °C and αa = 19.6 × 10−6,
  αb = 9.1 × 10−6, αc = 8.8 × 10−6, αV = 37.6 °C−1 for the
  temperature range 500–900 °C. The direction of maximal
  thermal expansion is parallel to the chains of both MO6 octahedra
  and SiO4 tetrahedra, which can be explained by the
  stretching of silicate chains due to the increasing thermal vibrations
  of the Ba2+ cations. At 1000 °C, the titanosilicate
  framework in batisite collapses with the formation of
  fresnoite, Ba2TiSi2O7O.
metadata.lang: en_GB
metadata.name: dc.title
metadata.value: Batisite, Na2BaTi2(Si4O12)O2, from Inagli massif, Aldan, Russia: crystal-structure refinement and high-temperature X-ray diffraction study
metadata.lang: en_GB
resources.filename: 7.pdf
resources.url: https://dspace.spbu.ru/bitstream/11701/19309/1/7.pdf
resources.format: Adobe PDF
resources.size: 1,39 MB