Abstract
Raman studies on carbon-containing phases in nanosized-ZrO2/C and nanosized-(ZrC,ZrO2)/C composites. / A. Martiz, A. Farkas, Z. Karoly, F. P. Franguelli, S. K. Samaniego, A. Menyhard, L. Kotai. / Nano Studies. – 2021–2022. – # 21/22. – pp. 177-186. – eng. Raman spectroscopic studies were performed to identify the nature of the carbon-containing phases in nano-(ZrC,ZrO2)/C composites. The nano-ZrO2/C composites were prepared in a tube furnace by heat-treatment of zirconium-loaded sulfonated styrene-divinylbenzene resins between 1000 and 1400 °C. The plasma processing of a nano-ZrO2/C sample in inert or reducing atmosphere resulted in nano-(ZrC,ZrO2)/C composites. The Raman spectra of the nano-ZrO2/C samples show that the ratio of the amorphous carbon / graphitic components decreases, whereas the fraction of distorted graphite structures increases with increasing reaction temperature and time. This can be attributed to the formation of new graphene edges by the condensation of the polyene content in the amorphous carbon. The ratio of the amorphous carbon practically does not change if the plasma treatment was performed under inert (Ar+He) atmosphere. In contrast, under reducing (Ar+H2) atmosphere, the amorphous carbon almost completely crystallizes into graphite. The ratio of the defective / regular graphite structures and the change of the thickness or separation of the graphene (monolayer carbon) sheets are higher under inert than reducing plasma conditions. We found no catalytic effect of ZrC on the graphite crystallization under inert plasma conditions, but in the presence of H2, ZrC may catalyze the graphitization process. Fig. 3, Tab. 4, Ref. 40.