An electron microscopy study of the formation of hydroxyapatite through sol-gel processing

A study of the stages involved in the formation of hydroxyapatite synthesiz ed by a sol-gel route was performed using scanning and transmission electro n microscopic techniques as the primary characterization tools. Scanning el ectron microscopy enabled examination of the samples of the gel heat treate d at various temperatures and for different time periods to determine the m orphology and size of grains along with the presence and extent of any poro sity in the sample surfaces. Thus, phase development could be studied as a function of heat treatment time and temperature. The gel was prepared using calcium acetate and triethyl phosphate as precursors added in a Ca/P molar ratio of 1.67. Characterization of the samples using transmission electron microscopy allowed a closer examination of the interaction between individ ual particles and also the detection of features on a much finer scale. Res ults deduced from these techniques were compared with those obtained from X -ray diffraction and FTIR spectroscopy. (C) 1999 Kluwer Academic Publishers .