Thermal Analysis and Crystallization of Bioactive Glass “1d” in the SiO2-CaO-MgO-P2O5-CaF2-Na2O Compositional System

The crystallization behavior of the bioactive silicate glass “1d” was analyzed using non-isothermal conditions through differential scanning calorimetry (DSC). The plots carried out at different heating rates showed only one crystallization peak. The activation energy for crystallization was calculated through the equations proposed in the Kissinger and Matusita–Sakka models. The Johnson–Mehl–Avrami coefficient (n) was estimated by applying Ozawa and Augis–Bennet methods, resulting in a two-dimensional crystal growth. Crystalline phases which developed during high-temperature treatment were analyzed by X-ray diffraction and scanning electron microscopy. The activation energy for viscous flow was estimated to be 513 kJ/mol, which is lower than the activation energy for crystallization (539 kJ/mol). The Malek test highlighted that the crystallization process was more complex than a simple nucleation-growth mechanism. The sinterability parameter and Hruby coefficient showed the high stability of 1d glass against crystallization, which makes this bioactive material highly appealing for producing well-sintered products of biomedical interest, such as bioactive porous scaffolds for bone regeneration.