Stabilization of cubic CrN0.6 in CrN0.6/TiN superlattices

A transmission electron microscopy study of CrN0.6/TiN superlattices deposited by reactive magnetron sputtering is described. The stable structure of CrN0.60 is hexagonal, but high resolution transmission electron microscopy images of the superlattices showed that CrN0.6 layers ⩽10 nm thick were cubic, while 50 nm thick layers were hexagonal. That is, the cubic CrN structure was “epitaxially stabilized” by the cubic TiN, with which there is a 2.4% lattice mismatch. The superlattices with hexagonal CrN0.6 showed high strains and defect densities within ≈5 nm of each interface, presumably due to the 5.4% volume decrease associated with the cubic-to-hexagonal transformation. The effect of this strain on the transformation is discussed.