Bond-length analysis of the omega structure in Ti, Zr, Hf and their alloys: experimental data, new correlations and implications for chemical bonding models

An analysis is performed of the experimental information on the key interatomic distances (IDs) of the AlB2 type structure, the so-called omega (Ω) phase in Ti and Zr, as well as in Ti–V and Zr–Nb alloys. Various remarkable correlations are found between these IDs and standard measures of the atomic size, and with Pauling’s bond-lengths. These observations are discussed in the light of the phenomenological bonding pictures of the Ω structure, and with our recent ab initio calculations of the electronic structure of this phase.