Crystallisation and in vitro bioactivity of strontium and potassium- containing Na2O-CaO-SiO2-P2O5 glasses

S.N.Salama*, S.M.Salman, H.A.Abo-Mosallam,

National Research Center Egypt

The effect of K2O/Na2O and SrO/CaO replacements on the crystallization characteristics and in vitro bioactivity of glasses based on Na2O-CaO-SiO2-P2O5 system has been investigated. Combeite Na2Ca2Si3O9, sodium calcium silicate Na2Ca3Si6O16 and whitlockite Ca3(PO4)2, were identified as major crystalline phases in all the resultant glass-ceramics. No potassium and strontium-containing phases could be detected among the crystallization products of the glasses; it seems more likely that the potassium could be accommodated in the wollastonite structure, while strontium might be introduced in the sodium calcium silicate structure. Bioactivity of the glass-ceramic samples in simulated body fluid (SBF) was evaluated by examining the apatite layer formation on their surface using energy dispersive spectroscopy techniques, scanning electron microscopy; inductive coupled plasma and Fourier transform infrared reflection spectroscopy. Decrease in the bioactivity was observed as the Na2O was replaced by K2O. Strontium ions together with calcium in the apatite layer formed was detected with SrO/CaO replacement. The results help in understanding the evolution of the apatite surface layer with respect to the composition of the glass-ceramic. Key words: Cryatallization; Glass-ceramics; SBF; Bioactivity; Strontium; Potassium