title: Temperature-induced iron oxidation in bafertisite Ba2Fe42+Ti2(Si2O7)2O2(OH)2F2: X-ray diffraction and Mössbauer spectroscopy study
metadata.name: dc.date.accessioned
metadata.value: 2020-09-09T07:33:50Z
metadata.lang: -
metadata.name: dc.date.available
metadata.value: 2020-09-09T07:33:50Z
metadata.lang: -
metadata.name: dc.date.issued
metadata.value: 2017
metadata.lang: -
metadata.name: dc.identifier.uri
metadata.value: http://hdl.handle.net/11701/19310
metadata.lang: -
metadata.name: dc.description.abstract
metadata.value: The high-temperature behavior of bafertisite was studied by combination of techniques
  in order to characterize the temperature-induced iron oxidation associated with
  deprotonation of an octahedral layer. The chemical formula of bafertisite from Darai-Pioz
  alkaline complex (Tajikistan) determined by electron-microprobe analyzes and M¨ossbauer
  spectroscopy is Ba2.11(Fe2+
  2.70Fe3+
  0.17Mn1.09Zr0.04Na0.03) (Ti1
  .96Nb0.07)(Si2O7)2O2(OH1.29
  O0.65F0.06)F2. In situ high-temperature powder X-ray diffraction revealed abrupt shift ofreflections to the high-angle region and reduction of their intensity at T >525 ◦C. The
  M¨ossbauer spectroscopy studies indicated that the crystal structure of bafertisite contains
  Fe in octahedral sites as predominantly ferric ions with Fe3+/ Fe = 0.06, whereas bafertisite
  annealed at T = 600 ◦C has Fe in the same position with Fe3+/ Fe up to 0.39. The
  differential scanning calorimetry and thermogravimetric analyzes reveal the occurrence of
  a broad exothermic effect at T ∼ 537 ◦C associated with the mass loss corresponding to
  deprotonation. Since in the studied sample of bafertisite, Fe2+ apfu strongly prevails over
  OH apfu, the stoichiometric (charged-balanced) high-temperature oxidized modification
  cannot be obtained. In the paper, the high-temperature behavior of bafertisite is discussed
  and compared to that of astrophyllite.
metadata.lang: en_GB
metadata.name: dc.title
metadata.value: Temperature-induced iron oxidation in bafertisite Ba2Fe42+Ti2(Si2O7)2O2(OH)2F2: X-ray diffraction and Mössbauer spectroscopy study
metadata.lang: en_GB
resources.filename: 8.pdf
resources.url: https://dspace.spbu.ru/bitstream/11701/19310/1/8.pdf
resources.format: Adobe PDF
resources.size: 1,48 MB