Review of point defect structures in hexagonal close packed metals and across the Periodic Table

Abstract: We present a comprehensive ab initio dataset of formation energies and elastic properties of intrinsic point defects across all the transition and rare earth hexagonal close packed (hcp) metals, as well as metalloid elements with hcp crystal structure. Point defect properties appear weakly correlated with the c/a ratio of the hcp lattice. Instead, it is the position of an element in the Periodic Table that primarily defines the relaxation volume tensor, elastic dipole tensor and formation energy of a point defect. This suggests that the local variations in the electronic structure and interatomic bonding at the core of a defect dominate its properties, as opposed to long-range elastic deformations. Across all the metals, we find that the relaxation volumes of vacancies and self-interstitial defects are correlated with atomic volumes, with values of -0.35 and 1.46 atomic volumes for a vacancy and a self-interstitial defect, respectively, providing a universally good approximation independent of the crystal structure. This study complements and completes the existing point defect databases spanning body-centred cubic and face-centred cubic metals.