Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.73: Poster
Montag, 26. März 2012, 17:00–19:00, Poster B
Real structure characterization of shockwave-synthesized γ-Si3(O,N)4 — •Anke Köhler1, Christian Schimpf2, Thomas Schlothauer3, Volker Klemm2, Marcus Schwarz1, Gerhard Heide3, David Rafaja2, and Edwin Kroke1 — 1Institute of Inorganic Chemistry, TU Bergakademie Freiberg, Leipziger Str. 29, 09596 Freiberg — 2Institute of Materials Science, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 5, 09596 Freiberg — 3Institute of Mineralogy, TU Bergakademie Freiberg, Brennhausgasse 14, 09596 Freiberg
The spinel-type Si3N4 is known since 1999 and is counted among the hardest materials. It can be synthesized under high pressure only. Although the thermodynamic phase boundary is ∼ 12 GPa, usually large overpressures are required for shock wave synthesis of larger amounts of the material. The application of amorphous precursors and peak shock pressures ≥ 35 GPa enabled us to manufacture spinel-type material in the system Si-O-N without impurities of the low pressure modifications.
The global chemical composition of the synthesized samples was investigated by means of elementary analysis (EA) and SEM/EDX. The sample with the most perfect microstructure data obtained by X-Ray diffraction shows the lowest oxygen content. Detailed microstructure analyses of the Si3(O,N)4-nanopowder using high resolution TEM confirmed the expected spinel structure. However, they disclosed some extended crystal structure defects. EELS measurements showed much broader variation of the [O]/[N] ratios than expected.