Showing papers by "Mildred S. Dresselhaus published in 1984"
TL;DR: In this paper, the temperature variation of the in-plane thermal conductivity of benzene-derived carbon fibers (BDF) measured from 5 to 300K was discussed and very high thermal conductivities values-comparable to that of the best HOPG heat treated at the same temperature-were found.
46 citations
TL;DR: In this paper, the basic structure of intercalation compounds is described, where the atoms in each layer of the guest material are in registry with those in the neighboring layers of the host material.
Abstract: For the past decade, materials research has focused on synthesizing new materials and generating new structural arrangements that exhibit specific desired properties. Some of the greatest advances in this area have come out of work on intercalation compounds, which are formed by the insertion of atomic or molecular layers of a guest chemical species—an intercalant—between layers in a host material. Figure 1 illustrates the basic structure of intercalation compounds. Part a of the figure depicts graphite intercalated with lithium; this structure is described as “commensurate,” because the atoms in each layer of guest material are in registry with those in the neighboring layers of the host material. Part b of the figure shows the incommensurate nature of graphite intercalated with ferric chloride. Although graphite intercalation compounds have been synthesized for over 150 years, it is only very recently that methods have been perfected to the point that one can prepare materials with specific structures a...
46 citations
TL;DR: In this paper, the first step of graphitization of ion-damaged pyrolytic graphite at annealing temperatures of −2300 C was shown to be possible.
Abstract: Post-implantation annealing of ion-damaged, highly oriented pyrolytic graphite has been studied by Raman spectroscopy, ion-channeling techniques, and transmission electron microscopy. Complementary information obtained by these methods provides confirmation for the first step of graphitization of ion-damaged graphite at annealing temperatures of \ensuremath{\sim}2300\ifmmode^\circ\else\textdegree\fi{}C. This is manifested by the formation of carbon planes with two-dimensional ordering but no correlation in the third ($c$-axis) dimension.
29 citations
TL;DR: In the past few years, the focus of research in condensed-matter physics has shifted to exotic materials, novel structural arrangements, surfaces, interfaces and imperfect systems as discussed by the authors, which has already led to the discovery of new physics, such as the fractional quantum Hall effect.
Abstract: In the past few years, the focus of research in condensed‐matter physics has shifted to exotic materials, novel structural arrangements, surfaces, interfaces and imperfect systems. Advances leading to the fabrication of metal oxide–semiconductor devices and superlattice structures, for example, have made possible the study of quantum‐well structures and the discovery of the quantum Hall effect. After a decade of progress with this technology, combined with advances in computer‐controlled processing, we can now tailor composition and impurity profiles at an atomic level, monitor the effects that a fraction of a monolayer of atoms has on a surface and control the deposition of atoms layer by layer, capabilities that have already led to the discovery of new physics, such as the fractional quantum Hall effect. (See PHYSICS TODAY, July 1983, page 19.) Venkatesh Narayanamurti, in his article on page 24, captures the excitement of the strong interplay between basic physics and technology in condensed matter physics.
7 citations
TL;DR: In this article, the effect of sample temperature during implantation on the properties of the bismuth lattice was discussed, and the authors obtained a comparison of the As nearest neighbor distances in samples implanted at different temperatures.
Abstract: Magnetorefiection and preliminary Rutherford Backscattering channeling experiments indicate that point defects induced in the bismuth lattice by ion implantation are largely annealed out during the implantation process due to its low melting temperature of 271.3°C. These experiments also show that the implanted ions cause long range strains in the crystal. Single crystal bismuth samples have been implanted at low temperatures (from 273°K down to 77°K) with 75As to a total fluence of 5 × 1016/cm2 at energies ranging from 50 keV to 200 keV to yield an approximately constant arsenic profile from the sample surface to a depth of 625 A. To study the local environment of the implanted As ions, EXAFS measurements have been made at the Cornell High Energy Synchrotron Source (CHESS). From these data, we obtain a comparison of the As nearest neighbor distances in samples implanted at different temperatures. We discuss the effect of sample temperature during implantation on these properties. This work represents the first use of EXAFS to characterize annealing of implantation-induced lattice defects during the process of ion implantation.
TL;DR: In this article, the contact angles of benzene-derived carbon fibers with deionized water, aminopropyltriethoxy silane and du Pont 5878 polyimide solutions were measured.
Abstract: Measurements are reported of the contact angles of benzene-derived carbon fibers with de-ionized water, aminopropyltriethoxy silane and du Pont 5878 polyimide solutions. Both pristine fibers and fibers implanted with 5×1012 cm−2 and 1×1015 cm−2 fluences of 31p ions were investigated. Such implantation was observed to decrease the contact angle in all three solutions. The ion implantation had no significant effect on tensile strength, but did result in increased structural disorder (as reflected in the width of the main wide angle X-ray diffraction peak) and increased surface roughness. The increased disorder and roughness are believed to be principally responsible for the observed change in wetting angle.