Structure of the intermediate high-pressure phases of ternary lead tellurides

In chambers with diamond anvils, the structure of high-pressure phases of ternary lead tellurides Pb_1−x Sn_xTe (x = 0.29) and Pb_1−x Mn_xTe (x = 0.05) and nonstoichiometric crystals Pb_0.55Te_0.45, Pb_0.45Te_0.55 is analyzed by the synchrotron radiation diffraction method at pressures of P up to 14 GPa. The orthorhombic structure of the intermediate high-pressure phase (space group Pnma) is determined for all the samples above 6 GPa. Models of the phase transition in PbTe from the initial rock salt structure to the orthorhombic phase, which constitutes a distorted variant of NaCl, as well as the properties of this phase, are discussed.