Pressure-Induced Amorphization and Polyamorphism in One-Dimensional Single-Crystal TiO₂ Nanomaterials

The structural phase transitions of single-crystal TiO 2 −B nanoribbons were investigated in situ at high pressure using synchrotron X-ray diffraction and Raman scattering. Our results have shown a pressure-induced amorphization (PIA) occurred in TiO 2 −B nanoribbons upon compression, resulting in a high-density amorphous (HDA) form related to the baddeleyite structure. Upon decompression, the HDA form transforms to a low-density amorphous (LDA) form, while the samples still maintain their pristine nanoribbon shape. A high-resolution transmission electron microscopy (HRTEM) image reveals that the LDA phase has an α-PbO 2 structure with short-range order. We propose a homogeneous nucleation mechanism to explain the pressure-induced amorphous phase transition in the TiO 2 −B nanoribbons. Our study demonstrates for the first time that PIA and polyamorphism occurred in the one-dimensional (1D) TiO 2 nanomaterials and provides a new method for preparing 1D amorphous nanomaterials from crystalline nanomaterials.