Morphological effects on the transport and magnetic properties of polymeric and colloidal carbon aerogels

Journal Article · Thu Dec 15 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.18590· OSTI ID:7036141

Reynolds, G A.M. ^[1]; Fung, A W.P. ^[2]; Wang, Z H ^[3]; Dresselhaus, M S ^[4]; Pekala, R W ^[5]

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1. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
3. Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
4. Department of Physics, and Department of Electrical Engineering Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
5. Department of Chemistry and Materials Science, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The temperature-dependent conductivity, magnetoresistance, magnetic susceptibility, and room-temperature Raman scattering of carbon aerogel samples with different morphologies and various grain sizes are studied. In particular, carbon aerogels with a [ital polymeric] morphology are studied and compared with [ital colloidal] carbon aerogels. The conductivity exhibits an exp[[minus] [radical][ital T][sub 0]/[ital T]] dependence for all samples at low temperature. This strong localization behavior can be explained by a Coulomb-gap variable-range hopping mechanism, and this identification has been further corroborated by the low-temperature magnetoresistance data obtained in a magnetic field up to 15 T. Magnetic susceptibility measurements suggest that carbon aerogels with a smaller grain size are more disordered, in agreement with the conductivity data. The results suggest that the grains themselves, and not the defects within, act as carrier localization sites in these materials.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7036141
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:24; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
COLLOIDS
COULOMB FIELD
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRIC FIELDS
ELECTRICAL PROPERTIES
GRAIN SIZE
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETORESISTANCE
MICROSTRUCTURE
PHYSICAL PROPERTIES
POLYMERS
RAMAN SPECTRA
SIZE
SPECTRA
TEMPERATURE DEPENDENCE