Disparate Strain Dependent Thermal Conductivity of Two-dimensional Penta-Structures

Abstract

Two-dimensional (2D) carbon allotrope called penta-graphene was recently proposed from first-principles calculations and various similar penta-structures emerged. Despite significant effort having been dedicated to electronic structures and mechanical properties, little research has been focused on thermal transport in penta-structures. Motivated by this, we performed a comparative study of thermal transport properties of three representative pentagonal structures, namely penta-graphene, penta-SiC2, and penta-SiN2, by solving the phonon Boltzmann transport equation with interatomic force constants extracted from first-principles calculations. Unexpectedly, the thermal conductivity of the three penta-structures exhibits diverse strain dependence, despite their very similar geometry structures. While the thermal conductivity of penta-graphene exhibits standard monotonic reduction by stretching, penta-SiC2 possesses an unusual nonmonotonic up-and-down behavior. More interestingly, the thermal conductivity of penta-SiN2 has 1 order of magnitude enhancement due to the strain induced buckled to planar structure transition. The mechanism governing the diverse strain dependence is identified as the competition between the change of phonon group velocity and phonon lifetime of acoustic phonon modes with combined effect from the unique structure transition for penta-SiN2. The disparate thermal transport behavior is further correlated to the fundamentally different bonding nature in the atomic structures with solid evidence from the distribution of deformation charge density and more in-depth molecular orbital analysis. The reported giant and robust tunability of thermal conductivity may inspire intensive research on other derivatives of penta-structures as potential materials for emerging nanoelectronic devices. The fundamental physics understood from this study also solidifies the strategy to engineer thermal transport properties of broad 2D materials by simple mechanical strain.

Lower lattice thermal conductivity in SbAs than As or Sb monolayers: a first-principles study

“…However, the out-of-plane acoustic modes are still marked with ZA modes. It is clearly seen that LA and TA branches are linear near the Γ point, while ZA branch deviates from linearity, which shares the general feature of 2D materials [8][9][10][11][12][13][14][15][16][17][18][19][20] . It is clearly seen that both acoustic and optical branches overall move downward from As to SbAs to Sb monolayer, and the widthes of acoustic and optical branches gradually become narrow.…”

Anisotropic intrinsic lattice thermal conductivity of borophane from first-principles calculations

“…40 It is reported that the large contribution of the ZA mode to the κl of graphene is due to a symmetry selection rule which strongly restricts anharmonic phonon-phonon scattering of the ZA mode, resulting in much larger relaxation time of ZA mode compared to the in-plane acoustic branches. 39 However, the out-of-plane symmetry is broken in puckered structure such as phosphorene 46 , arsenene, 49 even pentagonal graphene, 50 where the symmetry-based phonon-phonon scattering selection rule doesn't work, leading to a larger scattering rate and shorter relaxation time of the ZA mode. As a result, the contribution of ZA mode in borohane, which is a 2D material of puckered structure, should be less than graphene.…”

From node-line semimetals to large-gap quantum spin Hall states in a family of pentagonal group-IVA chalcogenide

“…It is known that, from S atom to Te atom (also from C atom to Pb atom), the atomic radius becomes larger in the order of S < Se < Te (C < Si < Ge < Sn < Pb), thus the lattice constants and bond lengths should be increased correspondingly. As shown in the top view, one can see those 2D p-IVX 2 crystals are akin to the structure of experimentally identified pentagraphene and are composed completely of the pentagonal rings [46][47][48]. The summary of the topological states of the full 15 different p-IVX 2 based on HSE06 method is given in Fig.…”