The formation energy and interaction energy of point defects in ZrC

The formation energies of mono-vacancy and anti-site defect in ZrC have been calculated. The results are all in good agreement with experimental data and other theoretical reports. Then the formation energies of 28 transition metals (TMs) atoms substituting C or Zr atom, and locating at interstitial site have been obtained. Only Hf is energetically favourable to substitute Zr. The site preference of TMs in ZrC has also been investigated by using supercells and near neighbour Bragg Williams approximation. The formation energies of interstitial for 3d, 4d and 5d elements in ZrC indicate that all of the 28 TMs are hardly to locate the interstitial site in ZrC due to the large interstitial energies. A systematic study of interaction between the intrinsic vacancies of ZrC with TM impurity atoms has been performed by using first-principles calculations. The formation enthalpies, binding energies, electronic density of states and bond charge density for various defects and interactive configurations have been calculated. Finally, the results of site preference show that the interaction between the intrinsic defect and TM atom with C_Va+TM_C, C_Va+TM_Zr, and Zr_Va+TM_Zr configurations are almost attractive. Our results could be helpful in designing and improve the performance of ZrC alloy on demand.