The ongoing trend towards miniaturization in high-technology applications calls for efficient ways to fabricate large-area nanostructured film surfaces. Spontaneous pattern formation during heteroepitaxial growth is an elegant route towards this goal [1]. This will be demonstrated for SiGe films grown on vicinal Si(001) substrates. In this system, the growth front undergoes a series of strain-relief mechanisms that include the formation of {105}-faceted three-dimensional crystallites and the evolution of a dislocation network. By tuning substrate miscut and film thickness or growing superlattices a variety of patterns with different symmetries can be obtained. Recently, it has been demonstrated that ion erosion of compound semiconductors may also result in well ordered surface patterns [2]. On the technological most relevant silicon surfaces this method failed so far. However, by bombarding self-organized SiGe films the nanopatterns can indeed be transformed into the Si substrate. The details of the pattern transition and its dependence on ion energy are discussed in the framework of current theories of ion bombardment induced pattern formation.

Research supported by the FWF, Austria (No. P14009-TPH).

[1] C. Teichert, Phys. Rep. 365, 335 (2002)

[2] S. Facsko, et al. Science 285, 1551 (1999); F. Frost, et al., Phys. Rev. Lett. 85, 4116 (2000) .

The thin films are forming on the surface during friction with the composition and properties that are significantly different from the same characteristics of the base materials of the tribo-couples.

It is shown basing on the analysis of entropy balance that wear intensity of non-equilibrium surface films (dissipative structures) is lower that the same characteristic of equilibrium surface films. The conclusion is proved by the data for the ‘copper-graphite’ electric sliding contact.

Dissipative structures do not depend on initial conditions and are stable in a wide range of friction parameters. Thus the development of wear resistant materials should be based on the surface films studies. The investigations of the copper contact wires friction surfaces are performed and the mechanisms of the self-organization at different currents are determined; the leading role of carbon is shown. Finally a novel material is developed on the natural graphite matrix for current collectors applications. The self-organization of the developed material starts at lower currents compare to the traditional materials. The wear resistance and arc-resistance of the developed material is superior to the majority of traditional materials besides mechanical and conductive properties of the material are lower.

It is shown for stable conditions that the wear intensity drops due to entropy production decrease. An analytical equation is derived for current lubricating effect basing on Prigogine theorem. This equation is experimentally proved for different current collecting materials. It is shown that current lubricating effect is typical for dissipative surface structures. The process of self-organization starts with dissipative structures formation when the system passes the bifurcation point. It is shown using excessive entropy production as the Lapunov function that an instability is possible for tribo-system with current collection when the contact resistance decrease vs. current growth. This is also proved by experimental data.

Super- (H_v ~~ 40 - 70 GPa) and ultrahard (H_v ≥70 GPa in the range of diamond) nanocomposites which are prepared according to the generic design principle [1] under conditions of a strong thermodynamically driven segregation show not only a high hardness combined with a high elastic recovery limit and high resistance against cracks for-mation [2] but also a high thermal stability up to ≥ 1100°C [3] and a high tensile strength of 10 - 40 GPa that is approaching the ideal decohesion strength of flaw-free materials [4]. The absence of built-in defects can be understood in terms of a self-organization of the nanostructure during the growth. I shall summarize the experimental results from our work as well as from published papers of other authors which show that such a phase segrega-tion has many features that are characteristic of spinodal decomposition. A relatively small increase of hardness during the recrystallization of (TiZr)N [5,6] and (TiZr)C [5] coatings was reported and attributed to spinodal decomposition but this idea was not further substantiated and elaborated. I shall discuss the thermodynamic and kinetic parameters controlling the spi-nodal decomposition and the dependence of the crystallite size of the formed nanostructure on the properties of the phases. This will explain the discrepancies found in the recent published papers on the relatively low hardness enhancement (e. g. [7]) or its complete absence [8] in "Ti-Si-N" coatings prepared by different deposition techniques under conditions when the spinodal decomposition is thermodynamically or kinetically hindered. Furthermore, I shall also explain the recent findings that superhardness of 40-50 GPa can be obtained in nanocom-posites even if the crystallite size is larger than 10-20 nm.

[1] S. Veprek and S. Reiprich, Thin Solid Films 268 (1995) 64.

[2] S. Veprek and A. S. Argon, J. Vac. Sci. Technol. B 20 (2002) 650.

[3] H.-D. Männling, D. S. Patil, K. Moto et al., Suf. Coat. Technol. 146-147 (2001) 263.

[4] S. Veprek, S. Mukherjee, P. Karvankova, et al., J. Vac. Sci. Technol., 2003 (submit-ted)

[5] O. Knotek and A. Barimani, Thin Solid Films 174 (189) 51 [6] R. A. Andrievski, I. A. Anisimova and V. P. Anisimov, Thin Solid Films 205 (1991) 171

[7] [J. Patscheider, T. Zehnder and M. Diserens, Surf. Coat. Technol. 146-147 (2001) 201.

[8] W. J. Meng, X. D. Zhang, B. Shi et al., J. Mater. Res. 17 (2002) 2628.