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F. Klimashin, H. Euchner, P.H. Mayrhofer:
"Nitrogen vacancies - a key factor in synthesis of Mo-Al-N hard coatings";
Talk: 43rd International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego (USA); 2016-04-25 - 2016-04-29; in: "ICMCTF 2016", (2016), 25.

Here we show that cubic-structured Mo-Al-N coatings have a high potential to be used as wear-protection for various high-demanding applications. We have found that within this material system, nitrogen vacancies have a significant and determining role for the stabilization of the cubic structure - a necessary prerequisite for high thermal stability and strength. Whilst for solid solutions without N-vacancies the wurtzite-type structure is always energetically preferred, nitrogen vacancies favor the formation of the cubic phase. These ab initio predictions were experimentally verified with the help of magnetron sputtered Mo1-xAlxNy coatings. We could show for the first time, that the cubic phase can be maintained up to the very high Al-content of Al/(Mo+Al) ≈ 0.57. The significantly increased Al-content within the cubic phase for our sputtered Mo1-xAlxNy coatings suggests for an increased thermal stability and also helps to increase their hardness up to 38 GPa. (Further addition of Al results in a substantial softening to ~22 GPa as a consequence of the evolving wurtzite-type structure.)