OICC Press International Journal of Nano Dimension 2228-5059 1 1 2024 03 01 Sol-gel synthesis of FHA / CDHA nanoparticles with a nonstochiometric ratio 10.7508/ijnd.2010.0x.004 EN M. Shahmohammadi Department of Chemistry, Umea University ,Umea , Sweden. R . Jahandideh Biomedical Engineering Faculty, Islamic Azad University, Science and Research Branch, Tehran, Iran. A. Behnamghader Materials and Energy Research Center, Tehran, Iran. M. Rangie Department of Mechanical Engineering, Imam Hussein University, Tehran, Iran. Journal Article 2024 03 01 The aim of this study was to investigate the sol gel synthesis of HA/FA nanoparticles and the possible formation of TCP phase or unstoichiometric calcium deficient hydroxyapatite (CDHA) from the precursors with a Ca/P ratio of 1.62. In order to prepare the sol, the solutions of Triethyl phosphite, ammonium fluoride and calcium nitrate in ethanol were used respectively as P, F and Ca precursors.The crystallinity, particle and crystallite size, powder morphology, chemical structure and phase analysis were investigated by SEM, XRD, FT-IR and Zeta sizer experiment. A multiphase compound containing hydroxyapatite (HA) and fluoroapatite (FA) nanoparticles and calcium deficient hudroxyapatite (CDHA) agglomerates was obtained. The size of the crystallites estimated from XRD patterns using Scherrer equation and the crystallinity of HA phase were about 5 nm and 66% respectively. The zeta sizer experiments for the dispersed particles in its own conditions showed an average size of 98 nm.