Computational study of Raman spectra and vibrational modes at the interface between SiCO and free carbon

S Haseen and M Falgoust and P Kroll, CERAMICS INTERNATIONAL, 51, 23117-23123 (2025).

DOI: 10.1016/j.ceramint.2025.03.001

Understanding the interface between glassy SiCO and free carbon is indispensable to rationalizing many properties of SiCO ceramics. We conducted DFT calculations of Raman spectra for graphite, graphene, a polyaromatic hydrocarbon, and interface models between SiCO and carbon. The models were constructed with covalent Si-C bonds between SiCO and carbon ribbons as wide as 4 nm. The quantum-chemical calculations were complemented by MD simulations of large-scale SiCO models using a new machine-learning interatomic potential (MLIP). We find a single D-band for models with C-segregation larger than 3 nm. The D-and G-band intensity ratio, ID/IG, corresponds to the extent of C-segregation. The MLIP captures all significant trends in the vibrational density of states (vDOS) for interface models, agreeing with DFT calculations. Simulations of large-scale SiCO models with segregated carbon show that an increasing number of interfacial Si-C bonds decreases the position of the G-peak and increases the vibrational density in the D-band region. Therefore, the G-and D-band ratio is also sensitive to the interface structure between carbon segregation and amorphous SiCO matrix.

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