Elastic moduli and band gap of PbTe under pressure: ab initio study

In this work first principles calculations are performed to study the elastic moduli and energy band gap of PbTe under equilibrium and strained condition. Hydrostatic pressures are applied to bulk PbTe in rocksalt structure, and the results show that as the pressure increases, the bulk modulus, shear modulus and the C₁₁ component demonstrate a decreasing trend, whereas the C₁₂ component shows an improving trend. Energy band gap presents an unusual improving degrading trend with respect to pressure, with a band gap closure and reopening being observed. The predicted elastic moduli and band gaps can change over a wide range, which suggests that strain and pressure can be used as an efficient way to modulate the elastic and electronic properties. Furthermore, these findings are helpful in predicting the structural stability and band gap associated performance in PbTe based thermoelectric materials under pressure.