Crystallization study of sol-gel derived 13-93 bioactive glass powder

Multicomponent silicate bioactive glass (BG) (53SiO2‐20CaO‐6Na2O‐4P2O5‐12K2O‐ 5MgO in wt. %) (13-93 composition) was prepared via the sol-gel process. The influence of thermal treatment on the crystallization was evaluated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray nano-computed tomography (nano-CT). The temperature and time of the thermal treatment strongly influenced the formation of the crystalline phases. The preliminary outcomes demonstrate the possibility of tailoring the crystallinity of 13-93 BG powder in the range 5-43 wt. % by controlling the temperature and time of the heat treatment. The microstructure of powders sintered at two different temperatures (650 °C and 700 °C from 30 min to 4 h) was evaluated by TEM. X-ray nano-computed tomography (nano-CT) was used to visualize the 3D morphology and distribution of crystallization areas in the samples in powder form. A large range between the glass transformation and the crystallization temperatures is observed, which provides the prospect of a suitable material to manufacture directly 3D structures (e.g. porous scaffolds) without an intermediate processing step.