Arun S. Nissimagoudar

arXiv2025

BO-graphane and BO-diamane

The adsorption of boron and oxygen atoms onto mono- and multi-layer graphene leads to the formation of a buckled graphene layer (BO-graphane) and a 2D diamond-like structure (BO-diamane) sandwiched between boron monoxide layers per DFT calculations. BO-graphane has a calculated Young's modulus ($\it{E}$) of 750 GPA and BO-diamane 771 GPa, higher than the calculated $\it{E}$ of -F,-OH, and -H diamanes; this is due to the presence of B-O bonds in the functionalizing layers. Electronic band structure calculations show BO-graphane and BO-diamane are wide band gap semiconductors with an indirect band gap up to a thickness of three layers (3L). Phonon dispersion and $ab-initio$ molecular dynamics (AIMD) simulations confirm dynamic and thermal stability, maintaining structural integrity at 1000 K. The room-temperature lattice thermal conductivity of BO-graphane and BO-diamane is found to be 879 W/m.K and 1260 W/m.K, respectively, surpassing BeO (385 W/m.K), MgO (64 W/m.K), and Al$_2$O$_3$ (36 W/m.K); and F-diamane (377 W/m.K), and comparable to H-diamane (1145-1960 W/m.K), suggesting them as candidates for thermal management in applications.

cond-mat.mtrl-sci↗

arXiv2016

Diffusive nature of thermal transport in stanene

Using the phonon Boltzmann transport formalism and density functional theory based calculations, we show that stanene has a low thermal conductivity. For a sample size of 1$\times$1 $μ$m$^{2}$ ($L\times W$), the lattice thermal conductivities along the zigzag and armchair directions are 10.83 W/m-K and 9.2 W/m-K respectively, at room temperature, indicating anisotropy in the thermal transport. The low values of thermal conductivity are due to large anharmonicity in the crystal resulting in high Grüneisen parameters, and low group velocities. The room temperature effective phonon mean free path is found to be around 17 nm indicating that the thermal transport in stanene is completely diffusive in nature. Furthermore, our study brings out the relative importance of the contributing phonon branches and reveals that, at very low temperatures, the contribution to lattice thermal conductivity comes from the flexural acoustic (ZA) branch and at higher temperatures it is dominated by the longitudinal acoustic (LA) branch. We also show that lattice thermal conductivity of stanene can further be reduced by tuning the sample size and creating rough surfaces at the edges. Such tunability in the lattice thermal conductivity in stanene suggests its applications in thermoelectric devices.

cond-mat.mes-hall↗