<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>NaNO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> monolayer: A stable graphenelike supersalt with strong four-phonon scattering and low lattice thermal conductivity insensitive to temperature
Tingwei Li, Peng‐Hu Du, Ling Bai, Qiang Sun, Puru Jena
Abstract
Since the discovery of graphene, numerous efforts have been made to seek new two-dimensional (2D) graphenelike materials with intriguing properties. Here,we report a stable graphenelike supersalt ${\mathrm{NaNO}}_{3}$ monolayer composed of superhalogen ${\mathrm{NO}}_{3}$. The 2D ${\mathrm{NaNO}}_{3}$ monolayer is found to possess an ultralow isotropic Young's modulus (2.983 N/m) and a low thermal conductivity (1.65 W/mK @300 K), which is much lower than that of 2D NaCl monolayer (3.72 W/mK @300 K). We attribute this behavior to the strong anharmonicity induced by the weak bonding between Na and ${\mathrm{NO}}_{3}$ cluster and the large atomic displacements of O in the ${\mathrm{NO}}_{3}$ cluster. A giant four-phonon scattering leads to a 60% reduction in lattice thermal conductivity at 300 K compared to that of three-phonon scattering. Furthermore, temperature-induced phonon hardening causes the lattice thermal conductivity to be nearly temperature independent in the studied temperature range (100--350 K), displaying significant difference from the atom-based 2D materials.