High pressure structural phase transitions of TiO_2 nanomaterials

Recently, the high pressure study on the TiO₂ nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO₂ with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO₂ nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO₂ nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO₂ nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO₂-B nanoribbons. Various TiO₂ nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO₂ nanoribbons, α -PbO₂-type TiO₂ nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO₂ nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO₂ nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications.