Interplay between structure, stoichiometry and properties of technetium nitrides.

We report first-principles calculations of the structures and properties of technetium nitride phases within the framework of gradient-corrected density functional theory. Specifically, we have investigated the possible existence of hexagonal Tc(3)N and Tc(2)N subnitrides, following the recent discovery of Re nitrides analogues synthesized directly from the elements. These novel Tc subnitride phases, which are predicted to be stable, are also compared with bulk Tc and Tc mononitride in order to shed light on the intrinsic relationships between the structure, Tc/N stoichiometry, and properties in the Tc-N system.