Theory of Seebeck Coefficient in Multi-Walled Carbon Nanotubes

Shigeji Fujita, James McNabb III, Akira Suzuki

Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo, Japan.
Department of Physics, State University of New York, Buffalo, USA.

DOI: 10.4236/jmp.2013.45091                

Abstract

Based on the idea that different temperatures generate different conduction electron densities and the resulting carrier diffusion generates the thermal electromotive force (emf), a new formula for the Seebeck coefficient (thermopower) S is obtained: S=(2/3)ln2(qn)^-1ε_Fk_BD₀, where k_B is the Boltzmann constant, and q, n, ε_F, D₀ are charge, carrier density, Fermi energy, density of states at ε_F, respectively. Ohmic and Seebeck currents are fundamentally different in nature, and hence, cause significantly different behaviors. For example, the Seebeck coefficient S in copper (Cu) is positive, while the Hall coefficient is negative. In general, the Einstein relation between the conductivity and the diffusion coefficient does not hold for a multicarrier metal. Multi-walled carbon nanotubes are superconductors. The Seebeck coefficient S is shown to be proportional to the temperature T above the superconducting temperature T_c based on the model of Cooper pairs as carriers. The S follows a temperature behavior, , where T_g ^’= constant, at the lowest temperatures.

Keywords

Thermoelectric Power (Seebeck Coefficient); Multi-Walled Carbon Nanotubes; The Model of Cooper Pairs

Conflicts of Interest

The authors declare no conflicts of interest.

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