Features of Thermal behavior of Nanocrystalline Ceria in the Presence of Oxygen-Free Graphene

A comparative study of the morphology, phase composition, and thermal behavior of nanocrystalline ceria powder and graphene-containing composites based on it, which were synthesized using two methods combining sol-gel and sonochemical techniques, has been carried out. In one case, ceria crystallization occurred on the oxygen-free graphene sheets as a result of the interaction of Ce-containing sol and few-layer graphene suspension in an N,N-dimethyloctylamine-aqua emulsion. In another case, the graphene sheets were deposited on ceria nanocrystallites by combining the suspensions of ceria and graphene in an isopropanol-aqua mixture. It was found that the introduction of less than 1 wt % graphene leads to a decrease in the sintering temperature of nanocrystalline ceria by 175°C if the composite was obtained from a Ce-containing sol, and by 212°C if a nanocrystallite ceria was used for this purpose. The shapes of the shrinkage curves and shrinkage rates of composites also differ, and in both cases there are significant differences from the data for pure nanocrystallite ceria obtained under the same conditions.