Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route

Abstract

Cordierite gel was synthesized by non-hydrolytic sol-gel route, starting from aluminum chloride, TEOS and magnesium chloride dissolved in absolute ethanol. Crystallization of p.-cordierite from gel at temperatures between 900 and 1000 degrees C was confirmed by differential thermal analyses, X-ray and FTIR spectroscopy. Higher calcination temperature resulted in the transformation of mu- to alpha-cordierite. The value of Avrami parameter n = 2.23 for the mu-cordierite crystallization indicates contribution of different simultaneous mechanisms: homogeneous nucleation and three-dimensional crystallite growth due to homogeneity of gel and surface crystallization due to submicron particles of the gel.