Synthesis and Characterization of Arsenate/Phosphate Fluorapatite Solid Solutions

A series of arsenate-substituted fluorapatite (FA) was directly prepared through the aqueous precipitation method. Characterization studies from elemental analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, and scanning electron microscopy (SEM) have confirmed the formation of the arsenate/phosphate fluorapatite solid solutions (AsPFAs), i.e. , Ca 5 (P x As 1– x O 4 ) 3 F, which had a single phase of apatite structure. The analysis of the measurements indicated that the unit cell a and c parameters did not vary smoothly with the degree of substitution, as expected by Vegard’s law. The morphology was dependent of the arsenate/phosphate ratio. The solids with high As/(P + As) molar ratio of 0.29 to 1.0 were typically needlelike crystals, which developed along the c -axis; all apatites with the As/(P + As) molar ratio of