BIOACTIVITY OF 1.25CAO-CENTER-DOT-SIO2 GLASS - AN FTIR AND X-RAY STUDY ON POWDERED SAMPLES

Powdered samples (170-230 mesh) of a glass of composition 1.25 CaO . S iO2 were soaked in a simulated body fluid (SBF). The powders were subm itted to Fourier transform infrared transmission spectroscopy as coars e powders (such as drawn out from the SBF) and as fine powders (soaked and subsequently ground). Soaked samples were submitted to differenti al thermal analysis (DTA) and the crystalline phases formed during hea ting in the DTA apparatus were identified by means of X-ray diffractio n analysis. The method appears to be useful in studying the mechanism of deposition of the hydroxyapatite layer. It is documented, by using the same method, that the mechanism involves the reactions of hydrolys is and successive condensation and repolymerization of the silicate su bstrate. These reactions are very fast. Extensive Ca2+ cation depletio n occurs, but appears to be slower. (C) 1996 Elsevier Science Limited.