Size-Dependent Pressure-Induced Amorphization in NanoscaleTiO2

We investigated the size-dependent high-pressure phase transition behavior of nanocrystalline anatase ${\mathrm{TiO}}_2$ with synchrotron x-ray diffraction and Raman spectroscopy to 45 GPa at ambient temperature. Pressure-induced amorphization results in a high-density amorphous (HDA) form when the starting crystallite size is $<10\mathrm{nm}$. The HDA-${\mathrm{TiO}}_2$ transforms to a low-density amorphous form at lower pressures. Harnessing the nanometer length scale thus provides a new window for experimental investigation of amorphization in poor glass formers and a synthesis route for new amorphous materials.