Crystallization behavior of SiO2–P2O5–CaO–MgO–Na2O–K2O bioactive glass powder

Abstract The crystallization process of a bioactive silicate glass with 47.5SiO 2 -10Na 2 O-10K 2 O-10MgO-20CaO-2.5P 2 O 5 molar composition was investigated by using nonisothermal differential t hermal a nalysis (DTA). T he DTA plots recorded at different heating rates exhibited a single crystallization peak. The activation energy for crystallization was estimated by applying the equations proposed by Kissinger and Matusita-Sakka. The Johnson-Mehl-Avrami exponent (n) was assessed by using the Ozawa and Augis-Bennett methods. The analyses suggest that a surface crystallization mechanism with one-dimensional crystal growth is predominant. The activation energy for viscous flow was also assessed (176 kJ/mol) and was found lower than the activation energy for crystallization (271 kJ/mol). This confirms the stability of 47.5B against crystallization and its good sinterability, which is a highly attractive feature for producing glass products of biomedical interest, such as bioactive porous scaffolds for bone repair.

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