Electron-energy loss spectroscopy and Raman studies of nanosized chromium carbide synthesized during carbothermal reduction process from precursor Cr(CO)6

Nanosized chromium carbide has been prepared by metal–organic chemical vapour deposition (MOCVD) method in a fluidized bed and carburized in the mixture of CH4/H2 atmosphere in temperature range 700–850 °C. The carburization process involves carbon deposition on the outer surface of the Cr2O3 powder, followed by carbon diffusion into the powder, leading to formation of metastable Cr3C2−x phase and stable Cr3C2. The phase transformation from Cr2O3 to Cr3C2 via an intermediate state Cr3C2−x has been identified using electron-energy loss spectroscopy (EELS) and micro-Raman spectroscopy. We could hypothesize that the formation of carbon nanofilms surrounding the carbide crystallites provides the stress and assist the phase transformation from metastable Cr3C2−x to stable Cr3C2.