Dresden 2009 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 35: Poster Session II
MM 35.16: Poster
Wednesday, March 25, 2009, 16:30–18:30, P4
First-principles study of the structure and composition of Si3N4 surfaces and Si3N4/TiN interfaces — •Pawel Rodziewicz and Bernd Meyer — Interdisziplinaeres Zentrum fuer Molekulare Materialien (ICMM) und Computer-Chemie-Centrum (CCC), Department Chemie und Pharmazie Friedrich-Alexander-Universitaet Erlangen-Nuernberg
Due to its hardness as well as thermal and chemical stability, silicon nitride is frequently used as substrate and protective coating. Recently, superhard silicon nitride/titanium nitride-based nanocomposite materials have been synthesized which show a hardness similar to that of diamond. In order to obtain a better understanding of the surface and interface properties of these materials, density functional theory calculations have been applied to study the (0001), (1010), (1210), (1011), and (1211) surfaces of β-Si3N4. Surface reconstructions and saturation of the broken surface bonds with H, N, NH, and NH2 have been taken into account. The relative stability of the different surface compositions is analyzed in terms of surface phase diagrams, and Wulff constructions of the equilibrium shape of β-Si3N4 crystallites depending on the chemical environment have been obtained. Additionally, first results on the atomic structure and mechanical strength of coherent Si3N4(1010)/TiN(001) interfaces with different composition will be presented.