High-pressure effect on elastic constants, stacking fault energy and correlation with dislocation properties in MgO and CaO

Abstract

The elastic properties and the generalized-stacking-fault-energy (GSFE) in MeO (Me = Mg, Ca) under different pressures have been calculated using the first principle calculations. In the anisotropic elasticity theory approximation, by using the Foreman’s method, the core structure and Peierls stress of $\tfrac{1} {2}\left\langle {110} \right\rangle \left\{ {110} \right\}$ edge dislocation, screw dislocation and mixed dislocation in MgO and CaO within the improved Peierls-Nabarro (P-N) model in which the lattice discrete effect is taken into account have been investigated. The Peierls stresses of $\tfrac{1} {2}\left\langle {110} \right\rangle \left\{ {110} \right\}$ edge dislocation and screw dislocation in pure MgO obtained here are 40 MPa and 160 MPa, respectively, which are consistent with the previous calculations and the experiments. Furthermore, the dependence of the elastic constants, the generalized-stacking-fault-energy (GSFE), the core structure and the Peierls stress on pressure have also been discussed.