The important role of strain on phonon hydrodynamics in diamond-like bi-layer graphene

Abstract

In this work, combining first-principles calculation and the phonon Boltzmann transport equation, we explored the diffusive thermal conductivity of diamond-like bi-layer graphene. The converged iterative solution provides high room temperature thermal conductivity of 2034 W mK−1, significantly higher than other 2D materials. More interesting, the thermal conductivity calculated by relaxation time approximation is about 33% underestimated, revealing a remarkable phonon hydrodynamic transport characteristic. Significant strain dependence is reported, for example, under 5% tensile strain, room temperature thermal conductivity (1081 W mK−1) of only about 50% of the strain-free sample, and under 20% strain, it reduces dramatically to only about 11% of the intrinsic one (226 W mK−1). Unexpectedly, in addition to the remarkable reduction in the absolute value of thermal conductivity, tensile strain can impact the hydrodynamic significance. For example, under 5% strain, the underestimation of relaxation time approximation in thermal conductivity is reduced to 20%. Furthermore, using a non-equilibrium Green’s function calculation, high ballistic thermal conductance (2.95 GW m−2 K–1) is demonstrated, and the mean free path is predicted to be 700 nm at room temperature. The importance of the knowledge of phonon transport in diamond-like bi-layer graphene goes beyond fundamental physics owing to its relevance to thermal management applications due to the super-high thermal conduction.

Promising Thermoelectric Performance in Two-Dimensional Semiconducting Boron Monolayer

“…First, in contrast to graphene, in phosphorene and monolayer MoS 2 , the twelve atoms in the unit cell leads to thirty-six phonon branches. It was found that a complex crystal with many optical modes is usually associated with low lattice thermal conductivity ( Ding et al, 2018 ; Hu et al, 2020a ; Hu et al, 2020b ). A number of optical modes gather in frequency about 10 THz.…”

Fully Hydrogenated and Fluorinated Bigraphenes–Diamanes: Theoretical and Experimental Studies

“…The deformation of diamanes can significantly influence their thermal conductivity [13]; it is predicted that under 5% tensile strain, at room temperature, the thermal conductivity (1081 W/mK) is only about 50% of that of a strain-free sample, and under 20% strain, it is dramatically reduced to only about 11% (226 W/mK). Under applied external strain of 5% leads to the underestimation of the relaxation time with thermal conductivity reduction to 20% compared with strain-free condition.…”

“…Among the diamane, a structure with only one functionalized surface was also predicted, while an opposite surface was represented as an array of dangling bonds; this unique structure was called "diamondene" [7]. The unique properties of predicted and experimentally synthesized 2D diamonds-such as the high thermal conductivity [8][9][10][11][12][13], high hardness [3,14,15], excellent properties for electromechanical vibrators [12], optic peculiarities [16][17][18], and wide-gap spectra with many resonance peaks in valent and conductive bands in the density of states [17,18]-make such structures promising candidates for the main components in future nanoelectronics, optics and photonics.…”

High thermal conductivity driven by the unusual phonon relaxation time platform in 2D monolayer boron arsenide

“…8 Inspired by the ultra-high thermal conductivity of graphene, 9 the researches on thermal transport in low-dimensional system have attracted extensive attention. [10][11][12][13][14][15][16] The decreased dimension induces quantum connement effect and alters the phonon dispersion, which further results in unique lattice thermal transport features. 17 In addition to graphene, Sahin et al 18 has proposed 13 different 2D III-V compounds of honeycomb lattice, seven of which (AlN, GaN, InN, BN, BP, BAs and BSb) have planer structure like graphene.…”