Reinvestigation of the crystal structure of Ca(2)Ce(8)(SiO(4))(6)O(2) apatite by Rietveld refinement.

Ca(2)Ln(8)(SiO(4))(6)O(2) apatites with Ln = La, Ce, Pr, Nd, Sm, Eu, Gd and Tb crystallize in space group P6(3)/m. The crystal structure of apatite-type Ca(2)Ce(8)(SiO(4))(6)O(2) [dicalcium octa-cerium hexa-kis-(silicate) dioxide], which has been synthesized by calcination, was refined from powder X-ray diffraction data using the Rietveld method. A database survey shows that contrary to the previously published Ca(2)Ce(8)(SiO(4))(6)O(2) structure [Skakle et al. (2000 ▸). Powder Diffr.15, 234-238], the cell volume of the structure reported here is consistent with those of other Ln apatites.