Ksenofontov D. A., Grebenev V. V., Zubkova N. V., Pekov I. V., Kabalov Yu. K., Chukanov N. V., Pushcharovsky D. Yu., Artamonova A. A.

Catapleiite behavior under heating and crystal structure of the product of its high-temperature transformation — the new phase Na₆Zr₃[Si₉O₂₇] with nine-membered rings of Si—O-tetrahedra

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2018. V. 147. N 3. P. 94-108

https://doi.org/10.30695/zrmo/2018.1473.07

Full text is available on eLIBRARY.RU

Language: Russian

Abstract

Thermal behavior of catapleiite, ideally Na₂ZrSi₃O₉2H₂O, has been investigated by means of X-ray diffraction, electroconductivity measurements using impedance spectroscopy, DSC, TG, and IR spectroscopy. The product of catapleiite high-temperature transformation obtained after annealing of catapleiite at 1000 °C was studied. This is a new microporous zirconosilicate, ideally Na₆Zr₃[Si₉O₂₇], representing a new structural type. It is hexagonal, Р6₃/mcm, a = 11.5901(9), с= 9.9546(9) Å, V = 1158.05(16) ų. Its crystal structure model was obtained using single-crystal XRD data and refined by the Rietveld method on the basis of powder XRD data (R = 3.87 %). The structure is based on the heteropolyhedral framework which essentially differs from that of catapleiite and is built by nine-member rings Si₉O₂₇ formed by SiO₄ tetrahedra connected with isolated ZrO₆ octahedra. Extra-framework Na cations are located in wide channels of the framework and between the tetrahedral rings Si₉O₂₇.

Key words: catapleiite, anhydrous sodium zirconium cyclosilicate, thermal behavior, electroconductivity, DTA, IR spectroscopy, crystal structure, Rietveld method.