Effect of initial pH value and atmosphereon fluorapatite preparation

The reproducibility of fluorapatite prepared by solution method is influenced by the initial pH value of the reaction. Here we prepared fluoapatite using a wet precipitation method, and the optimal initial pH value of fluorapatite formation was studied. Fluorapatite was preferentially formed under initial pH value of 12.30 prepared by the wet precipitation method, which is consistent with the pKɑ3 value of 12.3 for PO
4
³
-ions produced from HPO
4
²
- ions by hydrolysis reaction. At lower pH than 12.30, the competition of HPO
4
²
- and PO
4
³
- ions binding to Ca
²⁺
ions leads to the decrease of the crystallinity of calcium phosphate.