Pressure-induced amorphization and polyamorphism in TiO$_{2}$-B nanoribbons

The phase transitions of TiO$_{2}$-B nanoribbons were investigated with synchrotron X-ray diffraction and the Raman spectroscopy. Our results have shown 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. HRTEM image reveals that the LDA phase has an $\alpha $-PbO$_{2}$ structure with short range order. We propose a homogeneous nucleation mechanism to explain the PIA for the TiO$_{2}$-B nanoribbons. Our study demonstrates that PIA and polyamorphism occurred in the one-dimensional (1D) TiO$_{2}$ nanomaterials for the first time and provides a new method for preparing 1D amorphous nanomaterials from crystalline nanomaterials.