Analyzing the effect of composition, density, and the morphology of the ?free? carbon phase on elastic moduli in silicon oxycarbide ceramics

S Haseen and P Kroll, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 43, 1432-1441 (2023).

DOI: 10.1016/j.jeurceramsoc.2022.11.025

We perform atomistic simulations to model structures and calculate elastic properties of silicon oxycarbide ce-ramics. We explore individual parameters - composition, density, carbon content - to disentangle mutual de -pendencies that are difficult to separate in experimental studies. Each parameter is studied through dynamic simulations at finite temperatures for a wide range of temperatures. With multi-million atom models in simu-lation boxes as large as 40 nm, we reveal a hitherto "hidden" parameter: the morphology of the "free" carbon phase. Embedding, distribution, and interconnection of the carbon phase inside the amorphous matrix of SiCO severely impact the material's mechanical properties. As a consequence, we call for the development of new characterization techniques that will quantify the morphology of carbon in this and similar systems.

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