Mixed phosphate-sulfate fluor apatites as possible materials in dental fillers

A series of sulphate-phosphate apatites of formal composition Na (sub x) Ca (sub 10-x) (SO (sub 4) ) (sub x) (PO (sub 4) ) (sub 6-x) F (sub 2) (x = 1.2 to 6) were prepared by solid state reactions and hydrothermal techniques. Those produced from reactants Na (sub 2) SO (sub 4, ) CaSO (sub 4) , CaF (sub 2) and Ca (sub 3) (PO (sub 4) ) (sub 2) consisted of a mixture of two apatite end-members Na (sub 6) Ca (sub 4) (SO (sub 4) ) (sub 6) F (sub 2) and Ca (sub 10) (PO (sub 4) ) (sub 6) F (sub 2) contradicting previous work assuming a solid solution series between the end-members. The XRD patterns of the samples synthesized hydrothermally show a splitting of reflections interpreted as a monoclinic reduction of the hexagonal symmetry; these samples have the intermediate physical properties that are required for dental applications.