Impact of vacancies on structure, stability and properties of hexagonal transition metal diborides, MB2 (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, and Fe)

In this study, we have used density functional theory (DFT) calculations to characterize if and how defects influence the stability electronic/mechanical properties of M B 2 (AlB -type) for different transition metal . From a point defect analysis including vacancies, interstitials, anti-sites, identify vacancies be most favored, or least unfavored. To provide insight into possible vacancy ordering, focus on - B-sublattices nine metals ( = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W), modelled both as disordered ordered. We demonstrate explain why significant impact from Group 4 (Ti, Hf), 5 (Nb, Ta) 6 (Mo, W) with improved thermodynamical dynamical well mechanical properties. This by diverging ideal composition through controlled off-stoichiometry in terms B-deficient structures. Line compounds TiB , ZrB HfB account B-poor -rich conditions forming planar comprised vacant B. contrast ordered identified MoB WB an optimal result at 33.33% 25% B-vacancies, respectively, which significantly improves concurrent elimination antibonding states minimization non-bonding states. Similar behavior enhanced is demonstrated NbB TaB optimum around 10% 17% respectively.