“…A similar effect of the temperature elevation on Kaptiza resistance was observed for graphene-boron nitride hetero-nanosheets in the works done by Eshkalak et al . 47 and Liu et al 48 . Figure 7 The changes in Kapitza thermal resistance of six constructed grain boundaries A 1 (5–7–6–6–s), A 2 (5–7–6–s), A 3 (5–7–5–7–s), A 4 (5–7–6–6–a), A 5 (5–7–6–a), and A 6 (5–7–5–7–a) in BC 3 GrHs as a function of temperature at ΔT = 40 K and zero strain.…”
Simulation of thermal properties of graphene hetero-nanosheets is a key step in understanding their performance in nano-electronics where thermal loads and shocks are highly likely. Herein we combine graphene and boron-carbide nanosheets (BC3N) heterogeneous structures to obtain BC3N-graphene hetero-nanosheet (BC3GrHs) as a model semiconductor with tunable properties. Poor thermal properties of such heterostructures would curb their long-term practice. BC3GrHs may be imperfect with grain boundaries comprising non-hexagonal rings, heptagons, and pentagons as topological defects. Therefore, a realistic picture of the thermal properties of BC3GrHs necessitates consideration of grain boundaries of heptagon-pentagon defect pairs. Herein thermal properties of BC3GrHs with various defects were evaluated applying molecular dynamic (MD) simulation. First, temperature profiles along BC3GrHs interface with symmetric and asymmetric pentagon-heptagon pairs at 300 K, ΔT = 40 K, and zero strain were compared. Next, the effect of temperature, strain, and temperature gradient (ΔT) on Kaptiza resistance (interfacial thermal resistance at the grain boundary) was visualized. It was found that Kapitza resistance increases upon an increase of defect density in the grain boundary. Besides, among symmetric grain boundaries, 5–7–6–6 and 5–7–5–7 defect pairs showed the lowest (2 × 10–10 m2 K W−1) and highest (4.9 × 10–10 m2 K W−1) values of Kapitza resistance, respectively. Regarding parameters affecting Kapitza resistance, increased temperature and strain caused the rise and drop in Kaptiza thermal resistance, respectively. However, lengthier nanosheets had lower Kapitza thermal resistance. Moreover, changes in temperature gradient had a negligible effect on the Kapitza resistance.
“…A similar effect of the temperature elevation on Kaptiza resistance was observed for graphene-boron nitride hetero-nanosheets in the works done by Eshkalak et al . 47 and Liu et al 48 . Figure 7 The changes in Kapitza thermal resistance of six constructed grain boundaries A 1 (5–7–6–6–s), A 2 (5–7–6–s), A 3 (5–7–5–7–s), A 4 (5–7–6–6–a), A 5 (5–7–6–a), and A 6 (5–7–5–7–a) in BC 3 GrHs as a function of temperature at ΔT = 40 K and zero strain.…”
Simulation of thermal properties of graphene hetero-nanosheets is a key step in understanding their performance in nano-electronics where thermal loads and shocks are highly likely. Herein we combine graphene and boron-carbide nanosheets (BC3N) heterogeneous structures to obtain BC3N-graphene hetero-nanosheet (BC3GrHs) as a model semiconductor with tunable properties. Poor thermal properties of such heterostructures would curb their long-term practice. BC3GrHs may be imperfect with grain boundaries comprising non-hexagonal rings, heptagons, and pentagons as topological defects. Therefore, a realistic picture of the thermal properties of BC3GrHs necessitates consideration of grain boundaries of heptagon-pentagon defect pairs. Herein thermal properties of BC3GrHs with various defects were evaluated applying molecular dynamic (MD) simulation. First, temperature profiles along BC3GrHs interface with symmetric and asymmetric pentagon-heptagon pairs at 300 K, ΔT = 40 K, and zero strain were compared. Next, the effect of temperature, strain, and temperature gradient (ΔT) on Kaptiza resistance (interfacial thermal resistance at the grain boundary) was visualized. It was found that Kapitza resistance increases upon an increase of defect density in the grain boundary. Besides, among symmetric grain boundaries, 5–7–6–6 and 5–7–5–7 defect pairs showed the lowest (2 × 10–10 m2 K W−1) and highest (4.9 × 10–10 m2 K W−1) values of Kapitza resistance, respectively. Regarding parameters affecting Kapitza resistance, increased temperature and strain caused the rise and drop in Kaptiza thermal resistance, respectively. However, lengthier nanosheets had lower Kapitza thermal resistance. Moreover, changes in temperature gradient had a negligible effect on the Kapitza resistance.
“…Similarly, for different structures, with increasing lengths from 20 to 100 nm, ITR has been associated with an increase of 21, 58, 58, and 34%. 3,24,28,32,37 When the structure length increases, more phonon modes with wavelengths will be excited because phonons can transit across the interface with fewer degrees of inelastic scattering and possess higher transmission rates, which make extra contributions to the thermal conduction and so the reduction of ITR. ITR does not change significantly by increasing the width.…”
Section: Resultsmentioning
confidence: 99%
“…The ITR decreased by 79.5% when the temperature increased from 100 to 600 K. The influence of temperature on the ITC and ITR has also been observed in other works. 25,32,33,38,39 By increasing the temperature, more high-frequency phonons are excited, and the interface inelastic phonon scattering increases, which simplifies the phonon transmission and improvement of the nonharmonic coupling. Therefore, ITR decreases with increasing temperature.…”
The
transport properties of hybrid nanostructures formed by graphene
and polyaniline (C3N) are investigated using molecular
dynamics simulations. We systematically explored various possible
atomic structures of the graphene/C3N interface (IF) and
their effects on the interfacial thermal resistance (ITR). Our results
initially showed that the zigzag interface yields a far better result
than the armchair interface in the thermal transport phenomenon. The
effects of temperature and structure length on the ITR were then studied.
Our findings show that increasing the temperature from 100 to 600
K and the length from 20 to 120 nm decreases the ITR by 79.5% and
63%, respectively. By applying a 7% strain on the structure, ITR and
heat flux increase and decrease by 56% and 15%, respectively, and
the temperature jumps by 32%. As the number of defects in the interface
increases, the ITR increases significantly. The phonon density of
state (PDOS) of the graphene and C3N structures, as well
as the atoms in both structures, have been analyzed to properly understand
the heat transfer in the interface. Finally, using the von Mises stress
formula, the stress distribution and concentration through the sheets
and interface in the presence of mechanical strains and various defects
are investigated. This work provides valuable information on the phonon
behavior of heat transfer in the synthesis of two-dimensional hybrid
graphene-based materials for use in nanoelectronic and thermoelectric
devices.
“…Thermal rectifiers usually can be constructed of two or more materials (hybrid) or in the mass graded systems [23][24][25][26][27]. A lot of investigation were implemented over thermal rectification using hybrid systems with graphene.…”
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