The crystallization kinetics of Na
2O·CaO·2SiO
2 (
x = 0) and 0.68ZnO·Na
2O·CaO·2SiO
2 (
x = 0.68, where
xis the ZnO stoichiometric coefficient in the glass formula) bioactive glasses have been studied using bothnonisothermal and isothermal methods. The results obtained from isothermal XRPD analyses have showedthat the first glass crystallizes into the isochemical Na
2CaSi
2O
6 phase, whereas the Na
2ZnSiO
4 crystallinephase is obtained from the Zn-rich glass, in addition to Na
2CaSi
2O
6. The activation energy (
Ea) for thecrystallization of the Na
2O·CaO·2SiO
2 glass is 193 ± 10 and 203 ± 5 kJ/mol from the isothermal in situXRPD and nonisothermal DSC experiments, respectively. The Avrami exponent
n determined from theisothermal method is 1 at low temperature (530
![](/images/entities/deg.gif)
C), and its value increases linearly with temperature increaseup to 2 at 607
![](/images/entities/deg.gif)
C. For the crystallization of Na
2CaSi
2O
6 from the Zn-containing glass, higher values of boththe crystallization temperature (667 and 661
![](/images/entities/deg.gif)
C) and
Ea (223 ± 10 and 211 ± 5 kJ/mol) have been foundfrom the isothermal and nonisothermal methods, respectively. The Na
2ZnSiO
4 crystalline phase crystallizesat lower temperature with respect to Na
2CaSi
2O
6, and the
Ea value is 266 ± 20 and 245 ± 15 kJ/mol fromthe isothermal and nonisothermal methods, respectively. The results of this work show that the addition ofZn favors the crystallization from the glass at lower temperature with respect to the Zn-free glass. In fact, itcauses an increase of
Ea for the Na diffusion process, determined using MD simulations, and consequentlyan overall increase of
Ea for the crystallization process of Na
2CaSi
2O
6. Our results show good agreementbetween the
Ea and
n values obtained with the two different methods and confirm the reliability of thenonisothermal method applied to kinetic crystallization of glassy systems. This study allows the determinationof the temperature stability field of the crystalline phases with the view of creating a different glass ceramicuseful in the field of bioactive materials.