Electronic and Mechanical Properties of Partially Saturated Carbon and Carbon Nitride Nanothreads

Carbon nanothreads (NTs) are ultrathin materials synthesized by solid-state reaction of crystalline benzene or pyridine under high pressure. Recent experimental studies show that the sp(2)-sp(3) conversion in C-C or C-N bonds toward NT formation is not always complete, typically resulting in samples constituted by a mixture of both partially and fully saturated structures. The objective of this study is to use density functional theory calculations to compute the mechanical and electronic properties of partially saturated carbon and carbon nitride nanothreads and analyze how they differ from those of conventional fully saturated NTs. The results show that partially saturated NTs have lower ideal strengths and stiffness compared to their fully saturated versions, but they are still remarkably strong. The electronic behavior varies from semiconducting to insulating, with band gaps in the range similar to 1.8-4.0 eV, while fully saturated NTs usually have wider gaps (>4.0 eV). These results show that partially saturated nanothreads can be used for the same applications previously suggested for fully saturated NTs on the basis of their outstanding mechanical strength, and novel applications may be envisioned due to their wider range of possible band gaps.