Structural phase transitions and the equation of state of SnTe at high pressures up to $2$ mbar

Synchrotron X-ray diffraction studies of the structure of SnTe have been performed at room temperature and high pressures under the conditions of quasihydrostatic compression up to $193.5$ GPa created in diamond anvil cells. Two structural phase transitions have been detected at $P\approx 3$ and $23$ GPa. The first phase transition is accompanied by a stepwise decrease in the volume of the unit cell by $4\%$ because of the orthorhombic distortion of the initial SnTe-$B_1$ cubic structure of the NaCl type. It has been found that two intermediate rhombic phases of SnTe with the space groups $Cmcm$ and $Pnma$ coexist in the pressure range of $3$–$23$ GPa. The second phase transition at $23$ GPa occurs from the intermediate rhombic modification to the SnTe-$B_2$ cubic phase with the CsCl structure type. This phase transition is accompanied by an abrupt decrease in the volume of the unit cell by $8\%$. The pressure dependence of the volumes per formula unit at room temperature has been determined.