Effect of oxygen interstitials on structural stability in refractory metals (V, Mo, W) from DFT calculations

Interstitial atoms have a significant influence on the structural, thermal and electronic properties and processes in refractory metals and their alloys. In the present study, the effect of oxygen impurity on the structure of pure V, Mo and W has been studied using Density Functional Theory (DFT) calculations. Single oxygen atom has been incorporated at the tetrahedral and octahedral sites to study the structural stability. In case of V and Mo, octahedral sites are energetically favorable, whereas for W, it is the tetrahedral site; this can be explained from the calculated values of formation energies for different V-O, Mo-O and W-O systems. A bcc to bct transition has been reported in all the systems with the introduction of interstitial oxygen atoms.