INTERFACIAL PRECIPITATION IN TITANIA-DOPED DIPHASIC MULLITE GELS

Interfacial precipitation in sol-gel derived, titania-doped diphasic m ullite gels was investigated using conventional and high resolution tr ansmission electron microscopy. Rutile, anatase, and brookite precipit ated on the interface between {110} planes of mullite and glass pocket s in the sintered body. The formation of brookite may be attributable to the Si-and Al-rich environment during precipitation. Each polymorph of titania has a unique morphology and orientation relationship with mullite. Brookite exhibits a truncated pill box shape, and anatase dis plays a vermicular morphology. Quenching experiments suggest that the precipitates grow and undergo phase transformations during cooling.