Exploration of thermal conductivity and optical properties of β- and γ-nitrogene

Abstract

In this paper, the thermal conductivity and optical properties of [Formula: see text]- and [Formula: see text]-nitrogene have been investigated by the first principles of density functional theory. Phonon dispersion suggests that [Formula: see text]- and [Formula: see text]-nitrogene are stable. The thermal conductivity of [Formula: see text]-nitrogene is almost isotropic and has a thermal conductivity of 960.17 W/m[Formula: see text]K at 300 K. The thermal conductivity of [Formula: see text]-nitrogene is anisotropic, which has a thermal conductivity of 12.34 W/m[Formula: see text]K and 18.59 W/m[Formula: see text]K along with the armchair and zigzag directions at 300 K, respectively. The acoustic phonon branches (TA, LA, and ZA) play a dominant role in heat transport in [Formula: see text]-nitrogene. But optical dispersions play an important role in the heat transport of [Formula: see text]-nitrogene. With the larger Grüneisen parameter and smaller phonon lifetime of [Formula: see text]-nitrogene, [Formula: see text]-nitrogene exhibits a smaller thermal conductivity than that of [Formula: see text]-nitrogene significantly. In addition, optical properties of [Formula: see text]- and [Formula: see text]-nitrogene have been researched. Meanwhile, [Formula: see text]-nitrogene has a certain absorption effect on the visible spectrum and ultraviolet light. Thus, the nitrogene allotropes have different optoelectronic properties. Moreover, nitrogene can be used to fabricate optoelectronic devices. This work provides a theoretical description of the thermal conductivity and photoelectricity of nitrogene allotropes.