APATITE FORMATION ON (2-X)CAO-CENTER-DOT-X 3 M(2)O(3)-CENTER-DOT-2SIO(2) GLASSES (M=LA,Y, 0-LESS-THAN-OR-EQUAL-TO-X LESS-THAN-OR-EQUAL-TO-0.6) IN A SIMULATED BODY-FLUID/

Glasses wer e prepared by substituting La2O3 or Y2O3 for CaO in glassy wollastonite composition (CaO . SiO2). Their behaviour when they are soaked in a simulated body fluid (SBF) was studied by means of an elec tron microscope equipped with an energy dispersive system for elementa l analysis, and by means of IR spectroscopy. Electron microscopy and e nergy dispersive microanalysis were performed on samples soaked as pol ished bulk samples, and 1R analysis was on samples soaked as fine powd ers. A carbonate-containing hydroxyapatite layer is formed when glasse s of low La2O3 content are soaked in SBF. When Y2O3-containing glasses are considered, even in the case of small substitution for CaO, the s ame layer forms only on fracture surfaces. The experimental results ag ree with the mechanism reported in the literature.