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Licensed Unlicensed Requires Authentication Published by De Gruyter (O) February 25, 2013

Synthetic murataite-3C, a complex form for long-term immobilization of nuclear waste: crystal structure and its comparison with natural analogues

Anna S. Pakhomova , Sergey V. Krivovichev , Sergey V. Yudintsev and Sergey V. Stefanovsky
From the journal

Abstract

The structure of synthetic murataite-3C intended for long-term immobilization of high-level radioactive waste has been solved using crystals prepared by melting in an electric furnace at 1500 °C. The material is cubic, F-43m, a = 14.676(15) Å, V = 3161.31(57) Å3. The structure is based upon a three-dimensional framework consisting of α-Keggin [Al[4]Ti12[6]O40] clusters linked by sharing the O5 atoms. The Keggin-cluster-framework interpenetrates with the metal-oxide substructure that can be considered as a derivative of the fluorite structure. The crystal chemical formula of synthetic murataite-3C derived from the obtained structure model can be written as [8]Ca6[8]Ca4[6]Ti12[5]Ti4[4]AlO42. Its comparison with the natural murataite shows that the synthetic material has a noticeably less number of vacancies in the cation substructure and contains five instead of four symmetrically independent cation positions. The presence of the additional site essentially increases the capacity of synthetic murataite with respect to large heavy cations such as actinides, rare earth and alkaline earth metals in comparison with the material of natural origin.


* Correspondence address: St. Petersburg State University, Department of Crystallography, University Emb. 7/9, 199034 St. Petersburg, Russische Föderation,

Published Online: 2013-02-25
Published in Print: 2013-03

© by Oldenbourg Wissenschaftsverlag, München, Germany

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