Citric acid effect on aqueous sol–gel cordierite synthesis

Cordierite was synthesized by a simple aqueous sol–gel route. Citric acid action as a chelant for the Al3+ ion, and for controlling phase segregation during the drying and initial thermal treatment of the gel, results in an amorphous precursor that crystallizes to μ-cordierite and spinel. The changes in the ratios of the crystalline phases, formed during dry gel calcination at 1000°C for 12 h were dependent on the ratio (L/M) of citric acid/Al3+ (mol/mol). For L/M3 and L/M5 samples, the ratio between the amount of μ-cordierite phase and the amount of spinel phase was the same, while, for the sample L/M1, the amount of μ-cordierite was larger than that found in the other samples.