Mechanisms of nonstoichiometry in HfN1-x.

Density functional theory is used to calculate defect structures that can accommodate nonstoichiometry in hafnium nitride: HfN_1-x, 0≤×≤0.25. It is predicted that a mechanism assuming simple distributions of nitrogen vacancies can accurately describe the variation in the experimentally observed lattice parameter with respect to the nitrogen nonstoichiometry. Although the lattice parameter changes are remarkably small across the whole nonstoichiometry range, the variations in the bulk modulus are much greater. [ABSTRACT FROM AUTHOR]