Nanolabyrinthine ZrAlN thin films by self-organization of interwoven single-crystal cubic and hexagonal phases

Abstract

Self-organization on the nanometer scale is a trend in materials research. Thermodynamic driving forces may, for example, yield chessboard patterns in metal alloys [Y. Ni and A. G. Khachaturyan, Nature Mater. 8, 410â€"414 (2009)] or nitrides [P. H. Mayrhofer, A. Hörling, L. Karlsson, J. SjölẤen, T. Larsson, and C. Mitterer, Appl. Phys. Lett. 83, 2049 (2003)] during spinodal decomposition. Here, we explore the ZrN-AlN system, which has one of the largest positive enthalpies of mixing among the transition metal aluminum nitrides [D. Holec, R. Rachbauer, L. Chen, L. Wang, D. Luefa, and P. H. Mayrhofer, Surf. Coat. Technol. 206, 1698â€"1704 (2011); B. Alling, A. Karimi, and I. Abrikosov, Surf. Coat. Technol. 203, 883â€"886 (2008)]. Surprisingly, a highly regular superhard (36 GPa) two-dimensional nanolabyrinthine structure of two intergrown single crystal phases evolves during magnetron sputter thin film synthesis of Zr0.64Al0.36N/MgO(001). The self-organization is surface driven and the synergistic result of kinetic limitations, where the enthalpy reduction balances both investments in interfacial and elastic energies. © 2013 Author(s).