Synthesis and characterisation of hydroxy/fluoroapatite solid solution

Hydroxyapatite (HA) and fluoroapatite (FHA) have been widely investigated as bone substitute and replacement materials. We report here the preparation of hydroxy/fluoroapatite solid solution using wet chemical precipitation method via brushite hydrolysis. Various amounts of sodium fluoride (1–5 mol%) were added during the preparation of hydroxyapatite to form hydroxy/fluoroapatite solid solution. The various experimental techniques like XRD, DTA, TGA, FT-IR and Vicker's hardness measurements were used to characterize the synthesized powders. Thermal analysis of the samples shows only the decomposition reaction of residues formed and the corresponding weight loss due to these reactions. The XRD data of all the samples calcined at 900°C shows well defined peaks of hydroxyapatite and fluoroapatite. The merging of (211) and (112) peak of apatite lattice in the FHA pattern indicates the formation of hydroxy/fluoroapatite solid solution. The decrease in the a-axis of HA lattice parameter indicates the substitution of F−ion in the OH−site of HA lattice. The FT-IR spectroscopic studies of the samples confirms the substitution of the F−ion in the OH−site of the HA lattice. The Vicker's hardness measurement shows that the hardness value of hydroxy/fluoroapatite solid solution is greater than the hydroxyapatite.