36 research outputs found
Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires
The thermal conductivity of silicon nanowires (SiNWs) is investigated by
molecular dynamics (MD) simulation. It is found that the thermal conductivity
of SiNWs can be reduced exponentially by isotopic defects at room temperature.
The thermal conductivity reaches the minimum, which is about 27% of that of
pure 28Si NW, when doped with fifty percent isotope atoms. The thermal
conductivity of isotopic-superlattice structured SiNWs depends clearly on the
period of superlattice. At a critical period of 1.09 nm, the thermal
conductivity is only 25% of the value of pure Si NW. An anomalous enhancement
of thermal conductivity is observed when the superlattice period is smaller
than this critical length. The ultra-low thermal conductivity of superlattice
structured SiNWs is explained with phonon spectrum theory.Comment: Nano Lett., ASAP Article 10.1021/nl0725998 S1530-6984(07)02599-4 Web
Release Date: December 21, 200
Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials
Recent years witnessed a rapid growth of interest of scientific and
engineering communities to thermal properties of materials. Carbon allotropes
and derivatives occupy a unique place in terms of their ability to conduct
heat. The room-temperature thermal conductivity of carbon materials span an
extraordinary large range - of over five orders of magnitude - from the lowest
in amorphous carbons to the highest in graphene and carbon nanotubes. I review
thermal and thermoelectric properties of carbon materials focusing on recent
results for graphene, carbon nanotubes and nanostructured carbon materials with
different degrees of disorder. A special attention is given to the unusual size
dependence of heat conduction in two-dimensional crystals and, specifically, in
graphene. I also describe prospects of applications of graphene and carbon
materials for thermal management of electronics.Comment: Review Paper; 37 manuscript pages; 4 figures and 2 boxe