Structural Transitions in Elemental Tin at Ultra High Pressures up to 230 GPa

Abstract

The crystal structure of elemental Sn was investigated by synchrotron X-ray diffraction at ultra high pressures up to ∼230 GPa creating in diamond anvil cells. Above 70 GPa, a pure bcc structure of Sn was observed, which is stable up to 160GPa, until an occurrence of the hcp phase was revealed. At the onset of the bcc-hcp transition at pressure of about 160GPa, the drop of the unit cell volume is about 1%. A mixture of the bcc-hcp states was observed at least up to 230GPa, and it seems that this state could exist even up to higher pressures. The fractions of the bcc and hcp phases were evaluated in the pressure range of the phase coexistence 160–230 GPa. The difference between static and dynamic compression and its effect on the V–P phase diagram of Sn are discussed.