Polymorphic transformations in nanostructured anatase (TiO$_2$) under high-pressure shock compression

The action of dynamic pressure and temperature on polymorphic transformations in nanostructured (grain size of 8–20 nm) anatase (TiO$_2$) is studied. The dynamic pressure of a loading pulse (10–45 GPa) is measured with a manganin gauge. The temperature of shock-compressed specimens, which is varied by varying the initial temperature and initial porosity, is found to fall into the range 500–2500 K. It is shown that as the temperature and shock compression pressure rise, the nanostructured anatase turns into a nanoanatase-nanocolumbite or columbite-rutile mixture or into almost impurity-free (pure) nanocolumbite or impurity-free microcrystalline rutile.