  Abnormal grain growth (AGG) was observed in rutile TiO2 formed by the thermal
treatment of anatase TiO2 in the presence of zirconium silicate. This
morphological behaviour was seen to occur in sintered powder compacts and thin
films with solid state zircon dopants and in TiO2 coatings on grains of zircon
sand. In order to clarify the mechanism of AGG in this system, various doping
methods were employed and the morphological consequences of these doping
methods were investigated. It was found that doping by Zr and Si does not give
rise to abnormal grain growth. The observed phenomena were discussed in terms
of morphological and energetic considerations. It is likely that a distinct
orientation relationship between rutile TiO2 and ZrSiO4 and possible grain
boundary liquid formation play a role in giving rise to the rapid growth of
faceted prismatic rutile.
