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graphite fibers
219
Abstracts moelectric power of highly oriented graphite between 1.5 and 280 K has been studied. Specimens were prepared from kish graphites and compression annealed graphites, and their resistivity ratio p3M)I(/p4,2K ranged between 5.8 and 26.9. Possibility of the new drag effect at around 4 K is suggested for all specimens investigated.
133. Kohler’s plots for the magnetoresistance of highly oriented graphite Y. Kaburagi and Y. Hishiyama (Musashi Institute of Technology, Setagaya-ku, Tokyo, 158, Japan). The
dependence of the magnetoresistance on magnetic field was measured at 77 and 4.2 K for kish graphite specimens with different crystallinity. Kohler’s plots were made for each temperature. At 77 K the plots for all specimens lie on a single curve at low fields. However, a definite single curve is not obtained at 4.2 K.
137. Physical properties of vapor-grown carbon fibers; investigations of the intercalation process with alkalimetals
K. Ohhashi, J. Amiell, P. Delhaes, J. F. Mareche, D. Guerard and M. Endo (CNRS Centre De Recherche Paul Pascal, Domaine Universitaire, 33405 Talence Cedex, France). Vapor grown carbon fibers
from benzene are actually the most graphitable fibers. The pristine fibers have been heat-treated at several temperatures (HTT”C) between 1000 and 2800°C. Their graphitation has been investigated by different technics: X-ray diffraction, magnetic susceptibility, d.c. electrical conductivity and Raman spectroscopy. The different carbon fibers have been doped with potassium and the resulting intercalation compounds studied by EPR.
138. Electrical fibers
properties
of intercalated
T. C. Chieu, M. S. Dresselhaus 1% Transverse electric field effect in graphite films Yoshiko F. Ohashi (Faculty of Science and Technology. Keio University, Yokohama, Japan). The elec-
trical resistivity along the basal planes of thin graphite crystals was measured by applying electric field perpendicular to the basal planes of the crystal surface at liquid helium temperature. The variety of the field dependence of resistivity may be ascribed to the structural imperfection.
graphite
and M. Endo
(MIT, Room 13-2090, 77Mass Ave., Cambridge, MA 02139, U.S.A.). Intercalation of the highly ordered
benzene-derived graphite fibers results in highly conducting, strong and thin conductors with resistivity values as low as 7j.&-cm at room temperature for acceptor-intercalated fibers that are air-stable and thermally stable. The temperature-dependent resistance, the thermal stability of the resistance and the magnetoresistance measurements of these intercalated fibers will be reported.
135. Influence of electron correlation in the interlayer force of graphite
Eugenio Gaite (Escuela de Zngenieria Tgcnica Zndustrial, Universidad de Valladolid). Matilde Lea1
139. Structure fibers
I. L. Kalnin,
and intercalation
of carbon/graphite
H. A. Goldberg,
J. B. Stamatoff
(Escuela Universitaria del Profesorado, Universidad de Santander). Emilio Santos (Departamento de Fisica Tedrica, Universidad de Santander, Spain). A model
(Celanese Research Company, Summit, NJ 07901, U.S.A.). I. L. Spain (Physics Department, Colorado State Universitv, Ft. Collins, CO 80.528, U.S.A.). It
of graphite is used consisting of a set of parallel ionic slabs immersed in an electron sea. Electronic structure of the regions between slabs is calculated from Thomas-Fermi-Dirac theory including corrections and correlation energy. Electron correlation gives a relatively small contribution to binding between layers.
was found that carbon fibers which are only twodimensionally ordered (“turbostratic”) can nevertheless be intercalated by strong acceptors (AsF,); and that such intercalation may be structurally well defined even at very low acceptor concentrations (high intercalation stages). The relationships between the long range structure and the intercalatability of different modulus carbon/graphite fibers are discussed.
136. One-dimensional electrical conductivity in glassy carbon
Dennis F. Baker and Robert H. Bragg (Materials
140. The thermal stability and the temperature de-
and Molecular Research Division, Lawrence BerkeIey Laboratory, and Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720, U.S.A.). A one-dimensional low
pendence of the resistance of PdC& and of CdCl, intercalated carbon fibers D. D. Dominguez and J. S. Murday (Code 6170, Naval Research Laboratory). Highly graphitized
temperature correction component of the electrical conductivity proportional to - T -‘/’ and appropriate to metallic filaments was found in glassy carbon. This term is a decreasing function of increasing heat treatment temperature from 1000 to 2200°C. Microstructural observations such as lattice imaging support this view.
pitch-based carbon fibers have been intercalated with PdCl, and CdCl,. These intercalated fibers were found to be thermally stable in a vacuum to at least 300 and 25O”C, respectively. Intercalation of these acceptors decreased the room temperature resistances of the fibers 10-l 5 times and caused their resistances to have a metallic dependence on temperature.
Abstracts moelectric power of highly oriented graphite between 1.5 and 280 K has been studied. Specimens were prepared from kish graphites and compression annealed graphites, and their resistivity ratio p3M)I(/p4,2K ranged between 5.8 and 26.9. Possibility of the new drag effect at around 4 K is suggested for all specimens investigated.
133. Kohler’s plots for the magnetoresistance of highly oriented graphite Y. Kaburagi and Y. Hishiyama (Musashi Institute of Technology, Setagaya-ku, Tokyo, 158, Japan). The
dependence of the magnetoresistance on magnetic field was measured at 77 and 4.2 K for kish graphite specimens with different crystallinity. Kohler’s plots were made for each temperature. At 77 K the plots for all specimens lie on a single curve at low fields. However, a definite single curve is not obtained at 4.2 K.
137. Physical properties of vapor-grown carbon fibers; investigations of the intercalation process with alkalimetals
K. Ohhashi, J. Amiell, P. Delhaes, J. F. Mareche, D. Guerard and M. Endo (CNRS Centre De Recherche Paul Pascal, Domaine Universitaire, 33405 Talence Cedex, France). Vapor grown carbon fibers
from benzene are actually the most graphitable fibers. The pristine fibers have been heat-treated at several temperatures (HTT”C) between 1000 and 2800°C. Their graphitation has been investigated by different technics: X-ray diffraction, magnetic susceptibility, d.c. electrical conductivity and Raman spectroscopy. The different carbon fibers have been doped with potassium and the resulting intercalation compounds studied by EPR.
138. Electrical fibers
properties
of intercalated
T. C. Chieu, M. S. Dresselhaus 1% Transverse electric field effect in graphite films Yoshiko F. Ohashi (Faculty of Science and Technology. Keio University, Yokohama, Japan). The elec-
trical resistivity along the basal planes of thin graphite crystals was measured by applying electric field perpendicular to the basal planes of the crystal surface at liquid helium temperature. The variety of the field dependence of resistivity may be ascribed to the structural imperfection.
graphite
and M. Endo
(MIT, Room 13-2090, 77Mass Ave., Cambridge, MA 02139, U.S.A.). Intercalation of the highly ordered
benzene-derived graphite fibers results in highly conducting, strong and thin conductors with resistivity values as low as 7j.&-cm at room temperature for acceptor-intercalated fibers that are air-stable and thermally stable. The temperature-dependent resistance, the thermal stability of the resistance and the magnetoresistance measurements of these intercalated fibers will be reported.
135. Influence of electron correlation in the interlayer force of graphite
Eugenio Gaite (Escuela de Zngenieria Tgcnica Zndustrial, Universidad de Valladolid). Matilde Lea1
139. Structure fibers
I. L. Kalnin,
and intercalation
of carbon/graphite
H. A. Goldberg,
J. B. Stamatoff
(Escuela Universitaria del Profesorado, Universidad de Santander). Emilio Santos (Departamento de Fisica Tedrica, Universidad de Santander, Spain). A model
(Celanese Research Company, Summit, NJ 07901, U.S.A.). I. L. Spain (Physics Department, Colorado State Universitv, Ft. Collins, CO 80.528, U.S.A.). It
of graphite is used consisting of a set of parallel ionic slabs immersed in an electron sea. Electronic structure of the regions between slabs is calculated from Thomas-Fermi-Dirac theory including corrections and correlation energy. Electron correlation gives a relatively small contribution to binding between layers.
was found that carbon fibers which are only twodimensionally ordered (“turbostratic”) can nevertheless be intercalated by strong acceptors (AsF,); and that such intercalation may be structurally well defined even at very low acceptor concentrations (high intercalation stages). The relationships between the long range structure and the intercalatability of different modulus carbon/graphite fibers are discussed.
136. One-dimensional electrical conductivity in glassy carbon
Dennis F. Baker and Robert H. Bragg (Materials
140. The thermal stability and the temperature de-
and Molecular Research Division, Lawrence BerkeIey Laboratory, and Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720, U.S.A.). A one-dimensional low
pendence of the resistance of PdC& and of CdCl, intercalated carbon fibers D. D. Dominguez and J. S. Murday (Code 6170, Naval Research Laboratory). Highly graphitized
temperature correction component of the electrical conductivity proportional to - T -‘/’ and appropriate to metallic filaments was found in glassy carbon. This term is a decreasing function of increasing heat treatment temperature from 1000 to 2200°C. Microstructural observations such as lattice imaging support this view.
pitch-based carbon fibers have been intercalated with PdCl, and CdCl,. These intercalated fibers were found to be thermally stable in a vacuum to at least 300 and 25O”C, respectively. Intercalation of these acceptors decreased the room temperature resistances of the fibers 10-l 5 times and caused their resistances to have a metallic dependence on temperature.