Apatite formation on (2 − x)CaO·x/3 M2O3·2SiO2 glasses (M = La, Y; 0 less-than-or-equals, slant x less-than-or-equals, slant 0.6) in a simulated body fluid

Glasses were 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 electron microscope equipped with an energy dispersive system for elemental analysis, and by means of IR spectroscopy. Electron microscopy and energy dispersive microanalysis were performed on samples soaked as polished bulk samples, and IR analysis was on samples soaked as fine powders. A carbonate-containing hydroxyapatite layer is formed when glasses of low La2O3 content are soaked in SBF. When Y2O3-containing glasses are considered, even in the case of small substitution for CaO, the same layer forms only on fracture surfaces. The experimental results agree with the mechanism reported in the literature.