Influence of Pressure on the Structural, Electronic and Mechanical Properties of Cubic SrHfO₃: A First-Principles Study

The structural, electronic and mechanical properties of cubic SrHfO₃ under hydrostatic pressure up to 70 GPa are investigated using the first-principles density functional theory (DFT). The calculated lattice parameter, elastic constants and mechanical properties of cubic SrHfO₃ at zero pressure are in good agreement with the available experimental data and other calculational values. As pressure increases, cubic SrHfO₃ will change from an indirect band gap (Γ –R) compound to a direct band gap (Γ–Γ) compound. Charge densities reveal the coexistence of covalent bonding and ionic bonding in cubic SrHfO₃. With the increase of pressure, both the covalent bonding (HfO) and ionic bonding (SrO) are strengthened. Cubic SrHfO₃ is mechanically stable when pressure is lower than 55.1 GPa, whereas that is instable when pressure is higher than 55.1 GPa. With the increasing pressure, enthalpy, bulk modulus, shear modulus and Young's modulus increase, whereas the lattice parameter decreases. Moreover, cubic SrHfO₃ under pressure has higher hardness and better ductility than that at zero pressure.