Published online by Cambridge University Press: 28 February 2011
Transparent sols and gels in the ZrO2-SiO2 system containing 25, 50 and 75 mole % ZrO2 were prepared using tetraethyl orthosilicate (TEOS) and Zr n-propoxide solution in the presence of acids. Heating the gels to 600°C yielded an amorphous product which at higher temperature crystallized with formation of tetragonal and monoclinic ZrO2 . Zircon crystallized slowly at 1600°C. The results are explained by metastable liquid-liquid phase separation in the studied system.