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Virginie Aubin-Chevaldonnet, Philippe Deniard, Michel Evain, Aude Ysoline Leinekugel-Le-Cocq-Errien, Stéphane Jobic, Daniel Caurant, Václav Petricek, Thierry Advocat

Incommensurate modulations in a hollandite phase Ba_x(Al, Fe)_2xTi_8–2xO₁₆ intended for the storage of radioactive wastes: a (3+1) dimension structure determination

Keywords: Hollandite, Incommensurate modulation, Crenel function, q wave vector modulation, Single crystal structure analysis

Intensive researches on specific treatments of radioactive cesium, occurring in high level nuclear wastes, are in progress in France. Nowadays, a cesium immobilization in host matrices with a high chemical durability seems to be the favourite option. In that perspective, titanium based upon hollandite is a good candidate as a host matrix because of its high cesium incorporation ability, its excellent chemical stability, and its capacity to support charge compensation during the Cs⁺ into Ba²⁺ transmutation process. In this study we report the preparation and crystal growth in a BaF₂—B₂O₃ flux melt of the Ba_xCs_yM_zTi_8–zO₁₆ hollandite phase and its characterization by single crystal X-ray diffraction. An attention was focused on materials with M = Al or Al + Fe and with barium only since single crystals including cesium could not be obtained from the flux method. An incommensurate modulation of the Ba cation site occupancy, with I4/m(00γ)00 as a superspace group, was observed for all the single crystals under study.

Zeitschrift für Kristallographie, Oldenbourg Wissenschaftsverlag

Print ISSN: 0044-2968
Volume: 222, 08/2007
Pages: 383 - 390

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