The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method

Abstract

This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH4OH, Ca(OH)2-NH4H2PO4.The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca5H2O13P3 high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca9.04(PO4)6(OH)1.68, CaHPO4 at pH level 9 and CaPO3(OH), Ca(OH)2 at pH level 7.