Showing papers by "Mildred S. Dresselhaus published in 1981"
TL;DR: A broad review of recent research work on the preparation and the remarkable properties of intercalation compounds of graphite can be found in this paper, covering a wide range of topics from the basic chemistry, physics and materials science to engineering applications.
Abstract: A broad review of recent research work on the preparation and the remarkable properties of intercalation compounds of graphite, covering a wide range of topics from the basic chemistry, physics and materials science to engineering applications.
1,956 citations
TL;DR: The second-order Raman spectra are even more sensitive than the first-order spectra to the creation of lattice damage by ion implantation and to the subsequent partial restoration of graphite order by annealing as discussed by the authors.
Abstract: Ion-implanted graphite is studied by Raman scattering. Highly oriented pyrolytic graphite is implanted with $^{7}\mathrm{Li}$, $^{9}\mathrm{Be}$, $^{11}\mathrm{B}$, $^{12}\mathrm{C}$, $^{31}\mathrm{P}$, and $^{75}\mathrm{As}$ ions at 100 keV normally incident upon the $c$ face. Ion fluences in the range 1 \ifmmode\times\else\texttimes\fi{} ${10}^{14}$ to 2.5 \ifmmode\times\else\texttimes\fi{} ${10}^{16}$ ions/${\mathrm{cm}}^{2}$ are used. The lattice damage upon implantation is monitored by observation of the disorder-induced Raman line at \ensuremath{\sim} 1355 ${\mathrm{cm}}^{\ensuremath{-}1}$ in the first-order spectra and at \ensuremath{\sim} 2970 ${\mathrm{cm}}^{\ensuremath{-}1}$ in the second-order spectra. The Raman results indicate that an abrupt transformation to an amorphous surface layer occurs at a critical fluence which varies with the mass of the implanted ion. Results for first- and second-order Raman spectra are also presented for the same ion-implanted samples upon isochronal vacuum annealing at various annealing temperatures, showing a partial restoration of the graphite ordering. The second-order Raman spectra are even more sensitive than the first-order spectra to the creation of lattice damage by ion implantation and to the subsequent partial restoration of lattice order by annealing.
248 citations
32 citations
TL;DR: In this paper, a phenomenological model based on staging periodicity and in-plane superlattice symmetry is developed for the phonon dispersion relations of graphite intercalation compounds, analogous to the formalism developed for electronic dispersion relation.
Abstract: A phenomenological model based on staging periodicity and in-plane superlattice symmetry is developed for the phonon dispersion relations of graphite intercalation compounds, analogous to the formalism developed for the electronic dispersion relations. The formalism, based on the zone folding of the graphite dynamical matrix required by symmetry, gives with a minimum number of parameters the only available calculation for the phonon dispersion relations for high-stage compounds. Specific application of the model to a ${\mathrm{C}}_{2n}X$ structure yields results in good agreement with the stage dependence of the lattice mode spectra, indicating that the staging periodicity is the dominant effect in these compounds. Implications on the velocity of sound, second-order Raman spectrum, and specific-heat measurements are discussed.
20 citations
19 citations
TL;DR: In this article, the low-temperature variation of the in-plane thermal conductivity of graphite-FeCl/sub 3/intercalation compounds is reported, showing that the electronic contribution dominates in the liquid helium range.
19 citations
TL;DR: In this paper, the in-plane thermal conductivity and thermoelectric power of a stage-5 potassium donor graphite intercalation compound are reported in the temperature range 3 < T < 300 K.
17 citations
11 citations
TL;DR: In this paper, a model for the lattice modes for graphite intercalation compounds is presented, applicable to any intercalant and stage, based on the form of the dynamical matrix used by Maeda et al.
Abstract: A summary is given of the characteristics of the infrared and Raman lattice mode spectra of both donor and acceptor graphite intercalation compounds. To explain these observations, a model for the lattice modes for graphite intercalation compounds is presented. The model, applicable to any intercalant and stage, is based on the form of the dynamical matrix used by Maeda et al. for graphite. In addition to the known force constants for graphite, two additional parameters are introduced to account for the effect of intercalation. Calculated phonon dispersion relations and density of states curves are presented and related to experimental observations of lattice mode spectra.
11 citations
TL;DR: In this paper, the temperature dependence from 4.2 to 300k of the thermopower of a stage-2 graphite-FeCl3 intercalation compound is reported.
Abstract: The temperature dependence from 4.2 to 300K of the thermopower of a stage-2 graphite-FeCl3 intercalation compound is reported. The thermopower is found to be positive over all the temperature range and exhibits a temperature dependence quite different from that of pristine graphite.
9 citations
TL;DR: In this paper, a k z -axis zone folding model was applied to calculate the phonon density of states, velocity of sound, and elastic constants for intercalated graphite compounds.
TL;DR: In this article, the electrical conductivity of the polymer poly (p-phenylene sulfide) was studied as a function of temperature, ion energy, fluence and species, using a novel technique based on microelectronics processing.
Abstract: Ion-implantation can increase the electrical conductivity of the polymer poly (p-phenylene sulfide) (PPS) by ~ 14 orders of magnitude. This conductivity increase, which is stable under ambient conditions, is studied as a function of temperature, ion energy, fluence and species, using a novel technique, based on microelectronics processing, capable of accurately measuring conductivities as low as 10−10 (Ω-cm)−1. Mechanisms for the enhanced conductivity of PPS are discussed in relation to our measurements.