IN SITU SOL-GEL SYNTHESIS OF HYDROXYAPATITE CONTAINING HIGH 25% FLUORAPATITE NANOPOWDERS FROM CALCIUM NITRATE AND TRIETHYL PHOSPHITE PRECURSORS

摘要: In this study, hydroxyapatite (HA) containing 25% fluorapatite (FA)(HA-25% FA) nanopowders were simultaneously synthesized via sol-gel method. Ammonium fluoride (NH4F; MERK), calcium nitrate [Ca (NO3) 2, 4H2O; MERK] and triethyl phosphite [TEP,(C2H5O) 3P; MERK)] were used as F, Ca and P precursors respectively. Triethyl phosphite was first hydrolyzed in ethanol with a small amount of distilled water. To prepare HA-25% FA powder, an appropriate amount of the ammonium fluoride powder was added directly to TEP solution. The appropriate amounts of TEP solution was added dropwise to the calcium nitrate solution to yield a stoichiometric ratio of Ca/P= 1.67. The resulted solution stirred for 1 h and aged at 25 C for 24 h and 40 C for 72 h afterward. After oven drying at 80 C, the powder samples were heat-treated at 550 C for 1 h in air. Microstructural characteristics, powder morphology, chemical structure and phase analysis were performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) and Zetasizer instrument. The results of FTIR and XRD studies revealed that the partial substitution of the OHin hydroxyapatite by Foccurred and all two HA and FA phases were successfully formed. The FA/HA ratio measured from XRD pattern was about 0.32. The average particle size of powders evaluated by the zetasizer instrument in its own condition was 120 nm. Direct observation of the dispersed samples by TEM showed nanoparticles with a size of 20-40 nm. The crystallite size estimated from XRD patterns using Scherrer equation was 12 nm. An …