Non-isothermal crystallization kinetics for electrospun 3Al2O3·B2O3·2SiO2 ceramic nanofibers prepared using different silica sources

In this work, we present a comparative study on the non-isothermal crystallization kinetics for electrospun 3AB2S nanofibers prepared using colloidal silica (CS) and tetraethyl orthosilicate (TEOS) as silica sources. As-spun nanofibers with subequal mean diameters were obtained. Compared with those synthesized through CS, 3AB2S nanofibers prepared using TEOS have higher element homogeneity as a result of the simultaneous hydrolysis of Al and Si. They also show lower crystallinity, smaller mean grain size, higher crystallization temperature and higher activation energy owing to the stronger hindrance effect of uniformly distributed amorphous SiO2 on the reaction between Al2O3 and B2O3. Avrami constants values for Al4B2O9 crystallization together with TEM observations reveal an interface-controlled growth mechanism with instantaneous nucleation for both silica sources. However, those results indicate a two-dimensional grain growth when CS was used and a three-dimensional grain growth in the case of TEOS.