DFT study of interstitial hydrogen in tantalum lattice

Density Functional Theory computations are useful tools in the study of materials behaviour in presence of Hydrogen, and can be a valid help in the analysis of Hydrogen production processes and storage. In the present paper this technique is applied to Tantalum, a possible material for the realization of membranes for Hydrogen purification, resistant to highly corrosive environment (e.g. in the separation step in the Sulphur–Iodine process). A DFT study of the Tantalum lattice with interstitial Hydrogen at different concentrations is presented, with: a discussion on the preferential interstitial sites; a study of the displacements of Ta atoms caused by the Hydrogen presence, and of the interaction between two Hydrogens in the lattice; the calculation of the heat of solution and of the enlargement of the lattice at different Hydrogen concentrations; and, finally, the dependence of two elastic constants on the Hydrogen concentration, an important aspect in the study of the structural resistance of the material.