Absence of an Ideal Single-Walled Carbon Nanotube Forest Structure for Thermal and Electrical Conductivities

Abstract

We report the fundamental dependence of thermal diffusivity and electrical conductance on the diameter and defect level for vertically aligned single-walled carbon nanotube (SWCNT) forests. By synthesizing a series of SWCNT forests with continuous control of the diameter and defect level over a wide range while holding all other structures fixed, we found an inverse and mutually exclusive relationship between the thermal diffusivity and the electrical conductance. This relationship was explained by the differences in the fundamental mechanisms governing each property and the optimum required structures. We concluded that high thermal diffusivity and electrical conductance would be extremely difficult to simultaneously achieve by a single SWCNT forest structure within current chemical vapor deposition synthetic technology, and the "ideal" SWCNT forest structure would differ depending on application.

Elucidating the effect of heating induced structural change on electrical and thermal property improvement of single wall carbon nanotube

“…The wall number is known to affect the electrical properties, but its effect on the thermal properties has not been clarified [24]. In addition, crystallinity has been experimentally known to improve the thermal properties of SWCNT [26]. However, the connection between increases in thermal and electrical properties in this report could not elucidate which structure, wall number or crystallinity, more strongly affected the thermal and electrical properties.…”

“…Electrical sheet conductance (inverse of the sheet resistance) of the SWCNT forest before and after heat treatment was measured by a lithographically fabricated micro-4-probe as described in previous paper [25,26]. The conductivity of buckypaper was evaluated by a standard-sized 4-probe [25].…”

Diameter control of single-walled carbon nanotube forests from 1.3–3.0 nm by arc plasma deposition

“…In addition, previous approaches, which used the sparse distribution of catalysts on substrates, have demonstrated a coarse control over a substantial diameter range78910. Recently, the diameter control of SWCNT forests has also showed remarkable progress3334353637. The mean diameter of SWCNT forests, spanning 1.2–2.5 nm, has been reported by changing both the relative and absolute amounts of Co and Mo in a binary catalyst system34.…”

Exohedral Physisorption of Ambient Moisture Scales Non-monotonically with Fiber Proximity in Aligned Carbon Nanotube Arrays

“…[72] The presence of wall defects, which strongly influence the electronic properties of the CNTs (e.g. the dielectric permittivities), [43][44][45][46]74] may also contribute to the presence of Casimir interactions, which were previously shown to influence adsorption on CNTs. [65,75] The energetic and structural origin of the two modes observed here have yet to be elucidated.…”