When a graphite intercalation compound  is heated past a critical temperature, a large expansion along the c-direction occurs, giving the compound a puffed-up appearance. This phenomenom is known as exfoliation. Ubbelohde  observed that graphite-Br2 exfoliated at 350°C from 3 mm to approximately 35 mm. Exfoliation has also been observed in graphite-FeC13 , graphite-A1C13 , and graphite intercalated with a mixture of HNO3 and H2SO4 . The exfoliation of graphite-FeC13 has been used to manufacture Grafoil ; the exfoliation of graphite-(HNO3+H2SO) has been used for making a thermal insulator for molten metals . In spite of the numerous practical applications of exfoliation, relatively little work has been done to understand and characterize this unusual phenomenon.
KeywordsScanning Electron Microscopy Photograph Graphite Fiber Graphite Intercalation Compound Pristine Graphite Natural Graphite Flake
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