Titanium metal at high pressure: Synchrotron experiments and<i>ab initio</i>calculations

Abstract

The high pressure behavior of titanium metal is investigated experimentally using angle dispersive synchrotron x-ray diffraction as well as theoretically using ab initio electronic structure methods. Our calculations predict a direct \ensuremath{\omega} to bcc transformation around 80 GPa without any intermediate crystal phases. The ${\ensuremath{\beta}}^{\ensuremath{'}}$ (bcc-structure) Ti phase was experimentally observed to coexist with the \ensuremath{\omega} phase at pressures between 40 and 80 GPa on compression at ambient temperature. High-temperature treatment at 80 GPa results in a formation of a new \ensuremath{\eta} phase with a monoclinically distorted bcc structure. On decompression the \ensuremath{\eta} phase transforms to the pure ${\ensuremath{\beta}}^{\ensuremath{'}}$ phase.