Structural study of fluorapatite containing magnesium in substitution.

The crystal structure refinement of a serial of solid solutions Ca10-xMgx(PO4)(6)F-2, prepared with 2.5 ;5.0 ;10.0 ;15.0 ;20.0 and 30.0 atom% of magnesium, was carried out by the Rietveld method. Chemical analysis showed that the total incorporated magnesium in each solid solution was 2.3, 4.7, 9.6, 14.4, and 18.5 atom%, respectively. Those obtained by structural refinement indicated that the limit substitution was 16.8 atom%. Occupancy factors showed that magnesium prefer to occupy the site S(H); for ratios higher then 10 atom%, repartition became quasi-statistical. The substitution limit and the cationic repartition were con-elated to physicochemical propel-ties of the ions. (C) 2004 Academie des sciences. Publie par Elsevier SAS. Tous droits reserves.