Structural study of caesium-based britholites Sr7La2Cs(PO4)5(SiO4)F2

Several studies demonstrated the ability of britholites to retain radionuclides such as the caesium and actinides. Therefore, three compounds with formulas Sr8LaCs(PO4)(6)F-2, Sr7La2Cs(PO4)(5)(SiO4)F-2 and Sr2La7Cs(SiO4)(6)F-2, were prepared by solid state reaction. However, it seems that only the mono-silicated composition was obtained in a pure state. In this present work, the X-ray diffraction and magnetic nuclear resonance have been used to investigate the structure for this composition. The results showed that in fact this phase was not pure, but it was mixed with a secondary phase, SrLaCs(PO4)(2). The refinement by the Rietveld method allowed also to precise the distribution of La3+ and Cs+ ions between the two cationic sites of the apatite. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.