Interatomic distances in the stable and metastable bcc and omega structures of the transition metals: analysis of experimental and theoretical trends and correlations with Pauling's bond lengths

摘要

The name omega (#OMEGA#) phase refers to ahigh-pressure modification of the transition metals (TMs) Ti, Zr,and Hf. In alloys of Ti, Zr and Hf with other TMs, the #OMEGA#phase can be formed and retained metastably at room temperatureby quenching the bcc structure, which is usually the stable high-temperature phase in these alloy systems. As a part of a long-termresearch program on the structural and bonding properties of TMphases, we present in this paper a detailed analysis of the shortestinteratomic distances (SIDs) of the stable and metastable bcc and#OMEGA# structures of the 3d, 4d and 5d TMs, as well as theconnections between these and the single-bond length D(1)entering into Pauling' s classical bond length vs. bond numberrelation (BLBNR). The analysis involves an extensive databaseincluding experimental data, very recent ab initio calculations, andnew predictions based on the BLBNR for the bcc phase of the TMs.Our results lend support to early suggestions by Jamieson of theexistence of a correlation between D( 1) and the SID of the#OMEGA# phase of Ti and Zr. We also find that, for most TMs,D(1) and the SID of the #OMEGA# structure differ by less thanabout 2%, which implies that the Jamieson correlation might beconsidered as a reasonably accurate first approximation inestimating IDs and lattice parameters for unknown #OMEGA# phases of the TMs.