Characterization of graphene nanoplatelets-Si3N4 composites by Raman spectroscopy

Raman spectroscopy is a very useful tool to study composites containing carbon phases and in particular graphene based structures. For a Si3N4 composite containing 3 wt.% of graphene nanoplateletes (GNPs) fabricated by spark plasma sintering (SPS), the main characteristics observed in the Raman spectra and the images obtained by mapping specific graphene peaks are presented. Raman images evidence differences in the relative intensity of typical D, G carbon peaks for two different specimen orientations – perpendicular and parallel to the SPS axis – attributed to the GNP orientation. An interesting difference between the Raman spectra of the GNP composite and the Si3N4 specimen similarly processed is the presence of free Si in the blank specimen, whereas in the composite the presence of SiC is observed. Both the Si and the SiC are imaged by using corresponding peaks indicating their homogenous and similar distributions in both materials.