A density-functional calculation investigation was made of systematic trends in the self-interstitial atom defect behavior of body-centered cubic transition metals. In all of the non-magnetic body-centered cubic metals, the most stable self-interstitial atom defect configuration had <111> symmetry. Metals from group-5B of the periodic table (V, Nb, Ta) had significantly different energies of formation for the <111> and <110> self-interstitial atom configurations while, for group-6B metals (Cr, Mo, W), the 2 configurations were linked by a soft bending mode. The relative energies of self-interstitial atom defects in the non-magnetic bcc metals were fundamentally different from those in ferromagnetic body-centered cubic α-Fe. The systematic trend exhibited by the self-interstitial atom defect structures in groups 5B and 6B transition metals correlated with the observed thermally activated mobility of self-interstitial atom defects.

Self-Interstitial Atom Defects in BCC Transition Metals - Group-Specific Trends. D.Nguyen-Manh, A.P.Horsfield, S.L.Dudarev: Physical Review B, 2006, 73[2], 020101 (4pp)