Tiettaite K4Na12Fe3+Si16O41(OH)4 ⋅ 2H2O: A Mineral with a Novel Type of Microporous Heteropolyhedral Framework

T. L. Panikorovskii, I. V. Pekov, M. G. Krzhizhanovskaya, V. N. Yakovenchuk, S. N. Britvin, V. V. Gurzhiy, V. N. Bocharov, V. O. Yapaskurt, S. V. Krivovichev

Research output: Contribution to journalArticlepeer-review


Abstract: Microporous silicate tiettaite from the Khibiny alkaline massif (Kola Peninsula, Russia) has been studied using X-ray diffraction analysis, electron probe microanalysis, and Raman spectroscopy of single crystals and powders. Its chemical formula is refined to be K4Na12Fe3+Si16O41(OH)4⋅ 2H2O. The Raman spectrum of tiettaite contains lines at 3650, 3450, 1097, 1066, 980, 920, 681, 635, 569, 499, 458, 404, 272, 144 cm–1. The orthorhombic unit-cell parameters are a = 28.866(7) Å, b = 10.707(3) Å, c = 17.425(7) Å, V = 5385(3) Å3, Z = 4, sp. gr. Cmcm. The tiettaite crystal structure has been solved for the first time from single crystal and refined by the Rietveld method to the final Rwp = 2.47% and RBragg = 1.38%. The structure based on a new-type microporous heteropolyhedral framework formed by one-dimensional modules [Si28Na16Fe4K4O110]76– elongated along the c axis. Each module consists of complex ribbons with compositions of [Si14O39]22– and [Fe2K2Na6O32]50– compose a framework via shared vertices of half-occupied silicon–oxygen tetrahedra Si5 and Si6. Tiettaite structure contains a three-dimensional system of crossed channels with effective channel widths of 2.61 × 7.50, 2.46 × 2.92, and 3.60 × 3.90 Å2, running along the [100], [010], and [001] directions, respectively. The presence of a system of broad channels allows one to consider tiettaite as promising ion exchanger. Regarding the information complexity parameters, tiettaite can be assigned to minerals with very complex structure.

Original languageEnglish
Pages (from-to)76-85
Number of pages10
JournalCrystallography Reports
Issue number1
StatePublished - 25 Feb 2021

Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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