Ordering of calcium and vacancies in calcium catapleiite CaZr[Si3O9] • 2H2O
- Authors: Aksenov S.M.1,2, Portnov A.M.3, Chukanov N.V.4, Rastsvetaeva R.K.1, Nelyubina Y.V.5, Kononkova N.N.2, Akimenko M.I.2
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Affiliations:
- Shubnikov Institute of Crystallography
- Vernadsky Institute of Geochemistry and Analytical Chemistry
- Russian State Geological Prospecting University
- Institute of Problems of Chemical Physics
- Nesmeyanov Institute of Organoelement Compounds
- Issue: Vol 61, No 3 (2016)
- Pages: 376-382
- Section: Structure of Inorganic Compounds
- URL: https://journals.rcsi.science/1063-7745/article/view/189967
- DOI: https://doi.org/10.1134/S1063774516030020
- ID: 189967
Cite item
Abstract
A sample of holotypic calcium catapleiite from the Burpala alkaline massif (Northern Baikal, Russia) is studied by single crystal X-ray analysis at 120 K and IR spectroscopy. The empirical formula of calcium catapleiite is Ca0.97Na0.02Zr1.01Si3O9 • 2H2O (Z = 4). The X-ray diffraction study confirms the orthorhombic unit cell with the following parameters: a = 7.406(1), b = 12.687(1), and c = 10.112(1) Å; V = 950.1(2) Å3; space group Pbnn. The crystal structure is refined in the anisotropic approximation of atomic displacement parameters using 1177 reflections with I > 2σ(I) to the final R = 2.91%. The structure of calcium catapleiite under study is based on the microporous heteropolyhedral framework formed by ZrO6 octahedra and threemembered silicon–oxygen rings [Si3O9]. It is on the whole analogous to the structures of the samples studied earlier, but differs from them by a high degree of ordering of calcium and vacancies at extraframework positions. The distribution of calcium over Ca1 and Ca2 positions in the calcium catapleiite structure leads to the formation of zigzag chains of the …Сa1–Zr–Ca1–Zr… and …Сa2–h–Ca2–□… types. Low occupancy of the Ca2 position and its alternation with the vacancy are prerequisites for potential Ca2+ cationic conduction.
About the authors
S. M. Aksenov
Shubnikov Institute of Crystallography; Vernadsky Institute of Geochemistry and Analytical Chemistry
Author for correspondence.
Email: aks.crys@gmail.com
Russian Federation, Leninskii pr. 59, Moscow, 119333; ul. Kosygina 19, Moscow, 119991
A. M. Portnov
Russian State Geological Prospecting University
Email: aks.crys@gmail.com
Russian Federation, ul. Miklukho-Maklaya 23, Moscow, 117997
N. V. Chukanov
Institute of Problems of Chemical Physics
Email: aks.crys@gmail.com
Russian Federation, pr. Akademika Semenova 1, Noginskii raion, Chernogolovka, Moscow oblast, 142432
R. K. Rastsvetaeva
Shubnikov Institute of Crystallography
Email: aks.crys@gmail.com
Russian Federation, Leninskii pr. 59, Moscow, 119333
Yu. V. Nelyubina
Nesmeyanov Institute of Organoelement Compounds
Email: aks.crys@gmail.com
Russian Federation, ul. Vavilova 28, Moscow, 119334
N. N. Kononkova
Vernadsky Institute of Geochemistry and Analytical Chemistry
Email: aks.crys@gmail.com
Russian Federation, ul. Kosygina 19, Moscow, 119991
M. I. Akimenko
Vernadsky Institute of Geochemistry and Analytical Chemistry
Email: aks.crys@gmail.com
Russian Federation, ul. Kosygina 19, Moscow, 119991