“…3 we can also compute the heat flux value ( ) for the hot and cold slabs. Furthermore, this equality of the absolute amount of energy in the cold and hot baths is expected and aligned with the conservation of energy 43 . Figure 3 Accumulative energy changes in cold and hot slabs as a function of simulation time for graphene/graphane hybrid nanoribbon with a length of 20.42 nm at T = 300 K and ΔT = 40 K. …”
Optimization of thermal conductivity of nanomaterials enables the fabrication of tailor-made nanodevices for thermoelectric applications. Superlattice nanostructures are correspondingly introduced to minimize the thermal conductivity of nanomaterials. Herein we computationally estimate the effect of total length and superlattice period ($$l_{p}$$
l
p
) on the thermal conductivity of graphene/graphane superlattice nanoribbons using molecular dynamics simulation. The intrinsic thermal conductivity ($$\kappa_{\infty }$$
κ
∞
) is demonstrated to be dependent on $$l_{p}$$
l
p
. The $$\kappa_{\infty }$$
κ
∞
of the superlattice, nanoribbons decreased by approximately 96% and 88% compared to that of pristine graphene and graphane, respectively. By modifying the overall length of the developed structure, we identified the ballistic-diffusive transition regime at 120 nm. Further study of the superlattice periods yielded a minimal thermal conductivity value of 144 W m−1 k−1 at $$l_{p}$$
l
p
= 3.4 nm. This superlattice characteristic is connected to the phonon coherent length, specifically, the length of the turning point at which the wave-like behavior of phonons starts to dominate the particle-like behavior. Our results highlight a roadmap for thermal conductivity value control via appropriate adjustments of the superlattice period.
“…3 we can also compute the heat flux value ( ) for the hot and cold slabs. Furthermore, this equality of the absolute amount of energy in the cold and hot baths is expected and aligned with the conservation of energy 43 . Figure 3 Accumulative energy changes in cold and hot slabs as a function of simulation time for graphene/graphane hybrid nanoribbon with a length of 20.42 nm at T = 300 K and ΔT = 40 K. …”
Optimization of thermal conductivity of nanomaterials enables the fabrication of tailor-made nanodevices for thermoelectric applications. Superlattice nanostructures are correspondingly introduced to minimize the thermal conductivity of nanomaterials. Herein we computationally estimate the effect of total length and superlattice period ($$l_{p}$$
l
p
) on the thermal conductivity of graphene/graphane superlattice nanoribbons using molecular dynamics simulation. The intrinsic thermal conductivity ($$\kappa_{\infty }$$
κ
∞
) is demonstrated to be dependent on $$l_{p}$$
l
p
. The $$\kappa_{\infty }$$
κ
∞
of the superlattice, nanoribbons decreased by approximately 96% and 88% compared to that of pristine graphene and graphane, respectively. By modifying the overall length of the developed structure, we identified the ballistic-diffusive transition regime at 120 nm. Further study of the superlattice periods yielded a minimal thermal conductivity value of 144 W m−1 k−1 at $$l_{p}$$
l
p
= 3.4 nm. This superlattice characteristic is connected to the phonon coherent length, specifically, the length of the turning point at which the wave-like behavior of phonons starts to dominate the particle-like behavior. Our results highlight a roadmap for thermal conductivity value control via appropriate adjustments of the superlattice period.
“…Figure 6 shows the accumulated energy at the hot and cold slabs (temperature difference of 40 K) for the same graphene/biphenylene hybrid nanoribbon (length: 24 nm) and temperature conditions (room temperature: 300 K). The absolute value of heat flux ( dE dt ) at hot and cold slab is found to be equal to 110 eV ns −1 , which results in the same amounts of energy (as absolute values) in the cold and hot baths, as expected due to conservation of energy [32]. The interfacial thermal resistance at the grain boundary (Kapitza resistance, R k ) can be calculated using the following relation; see also [33]:…”
Section: Heat Transport In Graphene/biphenylene Hybrid Nanoribbonmentioning
Manipulating the thermal conductivity of nanomaterials is an efficacious approach to fabricate tailor-made nanodevices for thermoelectric applications. To this end, superlattice nanostructures can be used to achieve minimal thermal conductivity for the employed nanomaterials. Two-dimensional biphenylene is a recently-synthesized sp2-hybridized allotrope of carbon atoms that can be employed in superlattice nanonstructures and therefore further investigation in this context is due. In this study, we first determined the thermal conductivity of biphenylene at 142.8 W.m-1.K-1 which is significantly lower than that of graphene. As a second step, we studied the effect of the superlattice period ( ) on thermal conductivities of the employed graphene/biphenylene superlattice nanoribbons, using the molecular dynamics simulation. We calculated a minimum thermal conductivity of 105.5 W.m-1k-1 at = 5 nm which indicates an achieved thermal conductivity reduction of approximately 97% and 26% when compared to pristine graphene and biphenylene, respectively. This superlattice period denotes the phonon coherent length at which the wave-like behavior of phonons starts prevailing over the particlelike behavior. Finally, the effects of temperature and temperature gradient on the thermal conductivity of superlattice were also investigated.
“…Recently, numerous reports have shown that some carbonates and nitrides monolayers possess high mechanical and thermal conductivity. Two-dimensional (like graphene and carbon-nitride) nanomaterials are regarded as one of the most attractive research topics in a wide field by using a numerical simulation combined with experiments [19][20][21][22][23][24]. Graphene possesses high electrical [25], thermal conductivity [26], and mechanical properties since the exploration from 2004.…”
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