Role of Collective and Localized Modes on the Temperature-Dependent Thermal Conductivity in Polycrystalline C₆₀ Fullerite Compacts

Abstract

Recently observed thermal conductivity of polycrystalline C 60 fullerite compacts has been explained on the basis of a suggested dynamical model of the fullerites which takes into account the collective acoustic phonon modes with frequency dependent relaxation time and localized libronic and orientational diffusive modes with constant relaxation times, in the temperature range 0.7–300 K. Though the bulk of the conduction is via collective modes, the localized modes, too, contribute significantly to the total thermal conductivity.

On the Thermal Conductivity of Single-Walled Carbon Nanotube Ropes

“…Taking a cue from thermal conductivity when phonon distribution function is three-dimensional Debye type, one can suggest the form of ( )   to be that given by expression (8) where, d is introduced as a variable having the physical connotation of the dimensionality of the system. For d = 2, the expression corresponds to three-dimensional case [5]. Using this form of ( )…”

“…One must nevertheless, try to understand the phenomenon because of its commercial utility and also, for academic purposes, which will lead to the understanding of its different physical properties. An attempt here, is therefore, made to understand both the thermal conductivity and its intimately related quantity, the specific heat [5,6] using different physical dynamical models, and then try to fix the dynamical model, using the basic physics of the sample, to explain consistently both the temperarure dependent thermal conductivity and the specific heat variation of the sample.…”

Energy-dependent total thermal-neutron-scattering cross-section and transport of a neutron pulse in Fullerite at 300 K

“…Making use of this, one can write down the Boltzmann transport equation under diffusion approximation in the multigroup formalism as: (21) is known as Boltzmann_transport operator and is a (nxn) matrix where i=1,2,...,n and j=1,2,...,n; v = where vo = kT6D/mo) and E2 is expressed in terms of kBOD i.e. E = kHOD' D(E) are the diffusion coefficients given by…”