Search

The work reports a study of the processes of multilayer graphene (MLG) preparation using the action of microwave (MW) radiation on polyfluoridedicarbon intercalation compounds with general composition C2F·xR (R is chlorine trifluoride, acetone, acetonitrile, carbon tetrachloride, and benzene). Under the action of MW heating, these intercalation compounds undergo exfoliation (splitting) at temperature values that are 40–55% lower than in the case of traditional convective heating. It is shown that microwave heating increases the exfoliation degree and specific surface area of fluorinated graphite and decreases residual content of fluorine and chlorine in MLG. A key role in the process of MW exfoliation is due to the absorption of MW radiation by the polar dielectric intercalated into the interlayer space of fluorinated graphite. [ABSTRACT FROM AUTHOR]

An X-ray diffraction technique for the study of imperfect crystals of natural graphite and its fluorinated products is proposed. The diffraction patterns measured are free from the preferred orientation effect and provide the simulation based on a 1D disordered crystal. [ABSTRACT FROM AUTHOR]

The properties of intercalated compounds of graphite fluoride with highly volatile polar guest components were studied by DTA, XRPA, and IR spectroscopy. The role of guest host and host host intermolecular interactions in the formation of layered inclusion compounds based on polymer matrices with different degrees of fluorination is shown. [ABSTRACT FROM AUTHOR]

The energy level structure of fluorinated graphite intercalation compounds C2FxBr0.01· yCH3CN ( x = 0.49–0.87, y = 0.084–0.136) has been studied by X-ray photoelectron spectroscopy providing the information on the electronic structure of compounds in question. The analysis of variations of the binding energy of core levels C1 s, F1 s, and O1 s opens the possibility to explore the nature of the chemical bond C-F in the fluorographite matrix with a varying degree of fluorination, as well as to model the structure of these compounds. The examination of decomposition results of spectra into components has revealed the occurrence of C-F fragments, carbon atoms not bonded directly to fluorine atoms, and “graphite-like” areas, whose contribution to the overall structure increases with the degree of matrix fluorination decreasing. The presence of oxygen was considered from the viewpoint of surface phenomena characteristic of low-temperature carbon materials. [ABSTRACT FROM AUTHOR]

The paper reviews published data on the structure and composition of two large classes of inorganic polymer fluorocarbon materials (IP FCMs), including high‐temperature (HT) and low‐temperature (LT) modifications of graphite fluorides and fluorographite‐like compounds CFx (x = 0.5 – 1.12$) and CF1+y (y = 0.08 – 1.33$) and intercalated fluorographite compounds (IFGCs) based on CxF (x < 2) matrices. According to X‐ray diffraction data, C1s and F1s X‐ray photoelectron spectroscopy (XPS), 13C and 19F NMR, CKα and FKα X‐ray spectroscopy, and IR and Raman spectroscopy, as well as MNDO calculations, the structure of monolayers and the properties of IP FCMs of C2F – CF1+y composition depend on the combination of C(sp3) – F fragments bonded to the sp2 fragments of the starting carbon matrices. The structure of high‐temperature CF1+y is specified by the presence of structurally isolated external and internal C(sp3)F2 groups located on the boundaries of C(sp3) – F skeleton monolayers and in the holes of their nanostructures, respectively. The enthalpy of formation of HT FCMs does not depend on the type of starting carbon material and is linearly proportional to the F/C atomic ratio; C(sp3)F and C(sp3)F2 groups are chemically indistinguishable in HT FCMs. Six models for the structure of C2F and C4F monolayers in LT FCMs are considered. The best agreement with spectroscopy and MNDO data is obtained using modified Yudanov–Gornostaev's model for C2F, in which alternating rows of graphitelike sp2 carbon fragments coexist with rows of bonded perfluorocyclohexane sp3 cells. For low‐temperature C24F–C2F, electric conductivity and C1s and F1s XPS data are generalized and composition–property diagrams are constructed. In this case, the conductivity, C1s and F1s XPS, and the interplanar distances in monolayers are explained using the concept of planarity of CxF monolayers and the ensuing ideas of semi‐ionic and semicovalent C=F bonds. For C4F · yA–C2F · zA compositions, 13C and 19F NMR data, C1s and F1s XPS, and IR data are accounted for by the predominant sp3 nature of the structure‐forming C=F bonds. [ABSTRACT FROM AUTHOR]