Abnormal grain growth of rutile TiO2 induced by ZrSiO4

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. ⺠Large rutile crystallites in prismatic habit form when anatase is sintered in the presence of ZrSiO4. ⺠This abnormal growth is not observed in the presence of Zr, Si or ZrO2 dopants. ⺠There exists a unique orientation relationship between ZrSiO4 and rutile TiO2. ⺠AGG phenomena were discussed in terms of various possible mechanisms. ⺠Cumulative effects of multiple factors may impart AGG of rutile in the studied systems.