This article discusses the nature of radiation defects in graphite, reviewing past and recent developments in understanding their structure, interactions and effect on physical properties. The principal focus is on behaviour at the atomic and microstructural level, with an interest both in understanding graphite moderator damage in nuclear reactors and building a foundation for the range of emerging technological applications of defect-engineered graphitic materials. It is hoped that this article will both clarify the picture that has emerged over the last 50 years and provide a useful background to ongoing efforts.

Radiation defects in graphite

Effects of surface treatment on the bulk chemistry and structure of vapor grown carbon fibers

Measurements of the effect of uniaxial stress on the frequency of the k≊0 optical phonons in heat‐treated benzene‐derived graphite fibers have been performed using first‐order Raman scattering. Application of uniaxial stress along the fiber axis is found to cause polarization‐dependent splittings and shifts of the Raman peaks of the k≊0 doubly degenerate optical phonons. From these observed splittings and shifts, experimental values for the phenomenological coefficients which describe the changes in the elastic constant of these phonons with strain are determined. It is concluded that Raman spectroscopy can be used to characterize the local stress or strain conditions of graphite fibers nondestructively.

Effect of uniaxial stress on the Raman spectra of graphite fibers

A critical review of the novel physical properties and physical phenomena exhibited by ternary graphite intercalation compounds (TGICs) is presented. To facilitate discussion of TGICs they are classified according to their major structural features into four specific subgroups, namely homogeneous, heterogeneous, trilayer and localized. Within each subgroup particular compounds are further characterized as donor-donor, donor-acceptor and acceptor-acceptor. The preparation methods used to synthesize the materials addressed are briefly discussed as are the relevant chemical properties. The emphasis of this review is on the physics of TGICs and in particular the consequences of low-dimensionality. We show that, unlike binary graphite intercalation compounds, TGICs can be prepared with a broad range of compositions at constant stage. This feature and the enhanced interplanar and intraplanar structural variety exhibited by TGICs have stimulated a host of investigations which have extended our understan...

The physics of ternary graphite intercalation compounds

Publisher Summary The chapter presents a study on stage ordering in intercalation compounds. The chapter presents an analysis on the staging phenomenon. While the point of view is theoretical, connections and applications to experiment are emphasized. Although staging is observed in many types of intercalation compounds, the most numerous experiments and models have focused on graphite intercalation compounds. While some of the theory depends on particular electronic properties of graphite, the staging phenomenon is discussed in general terms. Most of the experimental examples are drawn from studies of intercalated graphite with a few examples from measurements on intercalated layered dichalcogenides. Recent reviews of the properties of intercalated graphite have emphasized the experimental consequences of the staging phenomenon. This chapter presents a discussion on the following conceptual and theoretical issues: the microscopic origin of the interactions responsible for staging, the phenomenon of staging phase transitions, and the kinetics of staging and intercalation. The discussion of these topics is preceded by a brief introduction to intercalation compounds (with emphasis on intercalated graphite) and an outline of the effects of stage ordering on the lattice, electronic, and transport properties of intercalated graphite.

Stage Ordering in Intercalation Compounds

Electron microscopy study of stage-2 graphite-SbCl 5

Raman microscopy of intercalated graphite fibers

The heat capacity ${C}_{p}$ of magnetic graphite intercalation compounds ${\mathrm{C}}_{\ensuremath{\xi}n}{(\mathrm{Co}{\mathrm{Cl}}_{2})}_{1\ensuremath{-}q}{(\mathrm{Al}{\mathrm{Cl}}_{3})}_{q}$ (stages $n=2,4,5$) is measured as a function of temperature ($3lTl25$ K) at zero and high (up to 14 T) magnetic fields ($\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}$ applied in plane). We are able to separate ${C}_{p}$ into its electronic, lattice, and magnetic contributions by suppressing the magnetic contribution to ${C}_{p}$ at the highest magnetic fields. The electronic heat capacity ${C}_{E}$ is observed to be small (for $Tg3$ K) compared with the lattice contribution ${C}_{L}$ which exhibits a ${T}^{2}$ temperature dependence characteristic of a two-dimensional phonon spectrum. The small value of ${C}_{E}$ is consistent with the results of our Fermi-surface measurements, which show excellent agreement with the predictions of the rigid-band model and $c$-axis zone folding. The magnetic heat capacity ${C}_{M}$ shows a broad peak at \ensuremath{\simeq} 9.1 K. The shape of this peak is consistent with the reported Monte Carlo calculations of ${C}_{M}$ based on a two-dimensional $\mathrm{XY}$ model.

L. Salamanca-Riba

Papers

Electron microscopy study of stage-2 graphite-SbCl 5

Raman microscopy of intercalated graphite fibers

Low-temperature Heat-capacity of Magnetic Graphite-intercalation Compounds

The effect of intercalation on the thermal conductivity of benzene-derived carbon fibers

The Ideal Resistivity of An Acceptor Graphite-intercalation Compound