Structure, solubility and bioactivity in TiO2-doped phosphate-based bioglasses and glass–ceramics

Phosphate-based bioactive glasses in addition to TiO2 (x = 0–2.5 mol%) were prepared by melt quenching technique. Glass–ceramics were prepared by controlled two-step thermal treatment of the as-prepared phosphate bioglasses at their nucleation and crystallisation temperatures. X-ray diffraction (XRD) analysis was used to explore the amorphous and crystalline nature of materials. The presence of calcium phosphate crystals like NaPO3, α, β-Ca2P2O7, α,β-Ca3(PO4)2 and Na5Ti(PO4)3 plays a dominant role in glass–ceramics. The structural changes were analyzed by density and Tg measurements. The degradation process in deionised water (DIW) was observed by pH and weight loss measurements. It was interesting to note that the highest solubility phosphate glasses become stiffer to degradation with increasing TiO2 content. Addition of TiO2 leads to densify the glass structure and interconnect the cross-linkages in the network. Chemical durability of glass–ceramics in DIW purely depends on the formed crystalline as well as the residual glassy phases. The formation of a biologically active layer on the surface of glasses and glass–ceramics were investigated by in vitro studies through XRD analysis.