Novel Carbon allotropes with mixed hybridizations: ene-C10, and ene-yne-C14. Crystal chemistry and first principles investigations

TL;DR

This paper introduces two new hybrid carbon allotropes, ene-C10 and ene-yne-C14, derived from C8 diamond-like structures, and investigates their crystal chemistry, stability, and electronic properties using first principles calculations.

Contribution

It reports the design, stability analysis, and electronic characterization of novel hybrid carbon allotropes with mixed hybridizations, expanding the understanding of carbon's structural diversity.

Findings

Both allotropes are mechanically and dynamically stable.

The structures exhibit metallic-like electronic behavior.

Thermal properties deviate from diamond with increasing openness.

Abstract

Based on C8, carbon 4C, with cfc topology, two hybrid carbon allotropes generated by inserting C(sp2) and C(sp1) carbon atoms into C8 diamond-like lattice were identified and labeled ene-C10 containing C(sp2) and ene-yne-C14 containing C(sp2 and sp1). The introduced double and triple chemical descriptions were illustrated from the projected charge densities. The crystal density and the cohesive energy were found to decrease due to the enhanced openness of the structures from inserted sp2/sp1 carbons, with a resulting decrease of the hardness along the series C8, C10, C12, and C14. The novel hybrid allotropes were found stable mechanically (elastic constants and their combinations) and dynamically (phonons band structures). The thermal properties from the temperature dependence of the heat capacity CV were found to increasingly depart from diamond-like C8 to higher values. From the electronic band structures, the inserted carbons were found to add up bands rigidly to diamond-like C8 while being characterized by metallic-like behavior for ene-C10 and ene-yne-C14.