Hetero-Orientation Epitaxial Growth of TiO₂ Splats on Polycrystalline TiO₂ Substrate

In the present study, the effect of titania (TiO₂) substrate grain size and orientation on the epitaxial growth of TiO₂ splat was investigated. Interestingly, the splat presented comparable grain size with that of substrate, indicating the hereditary feature of grain size. In addition, hetero- and homo-orientation epitaxial growth was observed at deposition temperatures below 400 °C and above 500 °C, respectively. The preferential growth of high-energy (001) face was also observed at low deposition temperatures (≤ 400 °C), which was found to result from dynamic nonequilibrium effect during the thermal spray deposition. Moreover, thermal spray deposition paves the way for a new approach to prepare high-energy (001) facets of TiO₂ crystals.