Self-organized Labyrinthine Nanostructure in Zr0.64Al0.36N Thin Films

• Self-organization of functional ceramics on the nanometer scale drives scientific and technological research in such diverse fields as cutting tools and light-emitting diodes. A classic example is spinodal decomposition in TiAlN thin films, which yields intricate nanostructures from the isostructural decomposition into cubic-structrure (c) AlN and TiN domains, resulting in age hardening [1]. Here, we explore the ZrN-AlN system, which has one of the largest positive enthalpies of mixing among the systems combining a transition metal nitride and a wide-band gap nitride [2]. Interestingly, an original nanolabyrinthine structure evolves during thin film synthesis of Zr0.64Al0.36N. It consists of the non-isostructural phases c-ZrN and wurtzite-AlN with standing {110}‖{112̄0} planes.The selforganization in this system is discussed in terms of a competition between interfacial and surface elastic energy, which produces a structure with a well-defined length scale. This effective nanostructural design yields films with hardnesses of 36 GPa, 44 % higher than comparable ZrN films.

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