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


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Language: Russian


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) Å3. 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.