First principles study of vacancy-solute complexes in vanadium

The solute atoms strong interaction with vacancy in vanadium plays an important role in the evolution of radiation-induced microstructure. We investigated the vacancy-solute atom interactions by first-principles calculations to obtain a better understanding for microstructure evolutions and the application of vanadium alloys. We calculated the binding energy between a vacancy and O/N atoms and stable configurations of VXn complexes (X = O/N) with n = 1-6. A vacancy can trap two O or N atoms. The VO and VO2 complexes dominate for VOn complexes, while the VN2 complex is more stable for VNn complexes. The electronic structure analysis show that the O/N atoms form bond with surrounding vanadium atoms while there is no direct interactions between two O/N atoms. The substitutional solute atoms (transition metals of Cr, Ti, Fe, Cu, Ni, Nb, Mo, Ta, W, Y; other important elements of Al, Si, S, P) interaction with a vacancy are also determined. Most binding strengths of vacancy-solute are in range of 0.10-0.40 eV while the vacancy-Ti/vacancy-Nb/vacancy-Ta/vacancy-Y interactions are strong attraction over 0.80 eV.