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

Cordierite gel was synthesized by non-hydrolytic sol–gel route, starting from aluminum chloride, TEOS and magnesium chloride dissolved in absolute ethanol. Crystallization of μ-cordierite from gel at temperatures between 900 and 1000 °C was confirmed by differential thermal analyses, X-ray and FTIR spectroscopy. Higher calcination temperature resulted in the transformation of μ- to α-cordierite. The value of Avrami parameter n = 2.23 for the μ-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.