Pressure-induced metallization phase transitions of PbSe and PbTe by electrical conductivity measurements and first principle methods

In situ electric conductivity measurements of PbSe and PbTe have been performed under high pressure in a diamond anvil cell. The results reveal the change of electron transport behaviors. As the pressure increased from ambient to 27 GPa, two and three abnormal conductivity changes were observed at room temperature in PbSe and PbTe, respectively. The abnormal conductivity changes in PbSe and PbTe can be ascribed to the structure phase transition. At high pressure, the conductivities in both PbSe and PbTe rise obviously and their values are near metal order. The first-principles calculations performed by CASTEP code based on the density functional theory illustrate that the direct band gap of PbTe vanishes at 15 GPa, which results in semiconductor to metal in PbTe. The results fully convinced that PbSe and PbTe can be metalized under pressure.