Synthesis and characterization of cordierite from acetylacetonate/alkoxide precursors

Syntheses of ultrafine glass powders in the MgO–Al2O3–SiO2 ternary oxide system were effected by drying and calcining sols derived from acetylacetonate-tetraethoxysilane ethanol solutions. A mixture of magnesium and aluminum acetylacetonates, dissolved with Si(OC2H5)4 in an ethanol solution in a 2:4:5 Mg: Al: Si mole ratio, was hydrolyzed, spray-dried, and calcined to yield a glass powder of 70 Å primary particle size, which sintered to densities ≥ 2.5 g/cm3 and which formed μ-cordierite as the only crystalline phase below 1000 °C. Incorporation of dopant quantities of boron and phosphorus, via their alkyl esters in the hydrolysis reaction with Si(OC2H5)4 and the acetylacetonates, afforded powders which crystallized in the α-phase directly after sintering to density = 2.66 g/cm3.