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The Characterization of Copper-Doped Carbon Aerogels by Transport Properties Measurements

Published online by Cambridge University Press:  11 February 2011

R.W. Fu ,
N. Yoshizawa ,
Y. Hanzawa ,
K. Kaneko ,
A. P. Santos ,
M. S. Dresselhaus ,
G. Dresselhaus ,
J. Satcher  and
T. Baumann
R.W. Fu
Affiliation:
Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, USA PCFM Laboratory, Zhongshan University, Guangzhou, 510275, China
N. Yoshizawa
Affiliation:
Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, USA National Institute of Advanced Industrial Science and Technology, Onogawa, Tsukuba, Japan
Y. Hanzawa
Affiliation:
Department of Chemistry, Faculty of Science, Chiba University, Chiba, Japan
K. Kaneko
Affiliation:
Department of Chemistry, Faculty of Science, Chiba University, Chiba, Japan
A. P. Santos
Affiliation:
Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, USA
M. S. Dresselhaus
Affiliation:
Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, USA
G. Dresselhaus
Affiliation:
Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, USA
J. Satcher
Affiliation:
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, USA
T. Baumann
Affiliation:
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, USA
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Abstract

Copper-doped carbon aerogels, which were prepared by sol-gel polymerization of a mixture of resorcinol, formaldehyde and copper ions, followed by supercritical drying with liquid CO2 and carbonization at different temperatures under a N2 atmosphere, were characterized by magnetic susceptibility and temperature-dependent conductivity measurements. The experimental results show that the magnetic susceptibilities (χ) of all the copper-doped carbon aerogels are larger than that of the blank carbon aerogel. The temperature-dependent magnetic susceptibilities of the copper-doped carbon aerogels are well fit to a Curie function in the low temperature region (below 45 K). According to the Curie constant obtained, the spin concentration (N) of the copper-doped carbon aerogels was calculated and the results show that the spin concentration of doped samples increases at first with an increase in the copper concentration used in doping, and then drops from the maximum in N and χ when the copper concentration is further increased above 0.1 wt%. Magnetic susceptibility results suggest that copper-doped carbon aerogels carbonized at 800 °C are more disordered than those carbonized at 1000 °C. The conductivity of these copper-doped carbon aerogels is apparently higher than that of the blank carbon aerogel, especially at low temperature (T < 45 K). The temperature-dependent resistivities of both the copper-doped and the blank carbon aerogels follow a linear functional form log ρ(T) ∼ (1/T)1/2 with two distinct regions below and above 45 K, indicating that the conduction of both the copper-doped and the blank carbon aerogels obey a tunneling and/or a hopping mechanism.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 734: Symposia A/B – Defect-Mediated Phenomena in Ordered Polymers – Polymer/Metal Interfaces and Defect Mediated Phenomena in Ordered Polymers , 2002 , B6.5
Copyright
Copyright © Materials Research Society 2003

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References

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