The influence of the phosphorus content on the bioactivity of sol-gel glass ceramics.

Abstract The aim of this work was to study the influence of the phosphorus on the crystallization and bioactivity of glass-ceramics obtained from sol–gel glasses. For this purpose two sol–gel glasses with a similar composition but one of them containing P 2 O 5 (70% SiO 2 ; 30% CaO and 70% SiO 2 ; 26% CaO; 4% P 2 O 5 , mol%) were prepared. Pieces of these glasses were treated at temperatures ranging between 700°C and 1400°C for 3 h. The obtained materials were characterized by XRD, FTIR, SEM-EDS and the biaxial flexural strength was determined in samples heated at 1100°C. In addition, an in vitro bioactivity study in simulated body fluid (SBF) was carried out. The results showed that phosphorus plays an important role in the crystallization of the glasses: it induced the crystallization of calcium phosphate phases, the stabilization of the wollastonite phase at high temperature as well as the crystallization of SiO 2 phases at low temperatures. Moreover, the presence of phosphorus produced a heterogeneous distribution of defects in the pieces and, therefore, the flexural strength of samples containing this element decreased. Finally, glass-ceramics obtained from glasses containing phosphorus showed the fastest formation rate of the apatite layer when soaked in SBF.