Abstract
Understanding the effect of edge relaxation in nanotubes (NTs) with two kinds of surfaces has been of central importance in the exploration thermal transportation properties for their applications in thermoelectric energy harvesting and heat management in nanoelectronics. In order to pursue a quantitative description of thermal transportation of SiNTs, we propose a theoretical model to deal with the lattice thermal conductivity by taking into account the sandwiched configurations based on the atomic-bond-relaxation correlation mechanism. It is found that the lattice thermal conductivity can be effectively tuned by different types of surface effect in Si nanostructures. As comparable to the Si nanowires and nanofilms, the SiNTs have the lowest thermal conductivity under identical conditions.
Highlights
Thermal conductivity of Si nanostructures can be significantly influenced by surface roughness, crystalline orientation and diameter, which can modulate the thermal transport properties.[11,12,13,14,15,16]
In order to address the effects of two types of surfaces, thickness and imposed temperature on the modulation of thermal transport properties in SiNTs, in this contribution we propose a theoretical method to approach the lattice thermal conductivity from the viewpoint of atomistic origin by taking into account a sandwiched configuration
T0 where η is the heat capacity of single atomic layer, r(R) is the inner radius, Ni( j) and N are the atomic number of inner surface and atomic number of bulk, zb is the coordination numbers (CNs) in bulk case, Ei( j) and Eb are the single bond energy in inner surface and that of the bulk counterparts at temperature T 0, ∆Ei( j)T and ∆ET are the energy gain of inner surface and that of bulk induced by imposed T, respectively
Summary
There has been an increased research interest in silicon nanostructures, including nanowires (NWs),[1] nanofilms (NFs)[2] and nanotubes (NTs)[3] because they exhibit exotic properties and potential applications such as components for nanoscale transistors, energy storage and photovoltaic devices.[4,5,6,7] In particular, thermal transport behavior in Si nanostructures has become increasingly important for understanding and designing new types of nanodevices.[8,9,10] Thermal conductivity of Si nanostructures can be significantly influenced by surface roughness, crystalline orientation and diameter, which can modulate the thermal transport properties.[11,12,13,14,15,16] the ultralow thermal conductivity of Si nanostructures as thermoelectric materials is highly desirable. A theoretical understanding of the influence of two types of surface relaxation of SiNTs involved in the thermal transport process is extremely important for the designing new types of nanodevices. In order to address the effects of two types of surfaces, thickness and imposed temperature on the modulation of thermal transport properties in SiNTs, in this contribution we propose a theoretical method to approach the lattice thermal conductivity from the viewpoint of atomistic origin by taking into account a sandwiched configuration. Theoretical results indicated that the bond identities of two kinds of surfaces show different responses under imposed temperature
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