Contribution of Embedded Bromine Molecules to the Dielectric Properties of Fluorinated Graphite Intercalation Compounds

• Published in: Journal of physical chemistry. C Vol. 127; no. 12; pp. 6010 - 6015
• Main Authors: Grebenkina, Mariya A., Chekhova, Galina N., Pinakov, Dmitry V., Shubin, Yury V., Asanov, Igor P., Bulusheva, Lyubov G., Okotrub, Alexander V.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 30-03-2023
• Subjects: C: Physical Properties of Materials and Interfaces
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.2c08830

Here, we study the dielectric properties of fluorinated graphites C2F x with different fluorine contents (x ≈ 1.05, 0.85, and 0.60) and embedded bromine molecules by impedance spectroscopy. An analysis of the results using the Maxwell-Garnett approximation made it possible to estimate the contributions of the fluorinated graphite matrix and bromine guests to the dielectric permittivity of the compound. The permittivity of the C2F x matrix increases with decreasing fluorine content and does not depend on temperature. The change in the permittivity upon cooling/heating of the samples is provided by the polarization of bromine molecules Br2. The significant temperature-dependent dielectric response of C2F0.60 is associated with the formation of bromine and polybromide ions, such as Br2 – and Br3 –, in the interlayer space of the matrix. The decrease in the permittivity at low temperature is explained by the freezing of the ion mobility.