Structural properties of protective diamond-like-carbon thin films grown on multilayer graphene

The Structure Properties of Carbon Materials Formed in 2,4,6-Triamino-1,3,5-Trinitrobenzene Detonation: A Theoretical Insight for Nucleation of Diamond-like Carbon

The structure and properties of nano-carbon materials formed in explosives detonation are always a challenge, not only for the designing and manufacturing of these materials but also for clearly understanding the detonation performance of explosives. Herein, we study the dynamic evolution process of condensed-phase carbon involved in 2,4,6-Triamino-1,3,5-trinitrobenzene (TATB) detonation using the quantum-based molecular dynamics method. Various carbon structures such as, graphene-like, diamond-like, and "diaphite", are obtained under different pressures. The transition from a C sp2- to a sp3-hybrid, driven by the conversion of a hexatomic to a non-hexatomic ring, is detected under high pressure. A tightly bound nucleation mechanism for diamond-like carbon dominated by a graphene-like carbon layer is uncovered. The graphene-like layer is readily constructed at the early stage, which would connect with surrounding carbon atoms or fragments to form the tetrahedral structure, with a high fraction of sp3-hybridized carbon. After that, the deformed carbon layers further coalesce with each other by bonding between carbon atoms within the five-member ring, to form the diamond-like nucleus. The complex "diaphite" configuration is detected during the diamond-like carbon nucleation, which illustrates that the nucleation and growth of detonation nano-diamond would accompany the intergrowth of graphene-like layers.

Evolution of the Microstructure, Hybridization, and Internal Stress of Al-Doped Diamond-Like Carbon Coatings: A Molecular Dynamics Simulation

This work modified some parameters related to the bond order in REBO-II of the C-C interaction and simulated the ta-C:Al film deposition using the large-scale atomic/molecular massively parallel simulator especially focused on the effect of the Al-doping content on the microstructural and mechanical properties of tetrahedral amorphous carbon films. According to the Al existence state, the Al content in the films can be divided into three ranges: range I─under 5 at % Al, a single Al atom or a small cluster with 2-3 Al atoms disperses separately in the matrix; range II─at 5-20 at. % Al, the number and incorporating Al atoms of the clusters increase with the Al content; range III─above 20 at. % Al, only a solid network of aluminum atoms forms, which becomes thickened and densified with Al content increment. The existence states of Al atoms play an essential role in determining mechanical and structural properties. With Al content increasing in the films, the isolated small cluster of atoms evolved into a whole network of aluminum inter-crossing with the C-network. With the evolution of Al existence states, the sp³C fraction decreases monotonically, while the sp²C fraction increases. In range III, the network of aluminum promotes the growth of sp¹C sites. The residual compressive stress in the film decreased rapidly with the Al content increasing in range I and II, but it reached a low-level constant value in range III.

Mixed sp2-sp3 Nanocarbon Materials: A Status Quo Review

Carbon nanomaterials with a different character of the chemical bond-graphene (sp2) and nanodiamond (sp3)-are the building bricks for a new class of all-carbon hybrid nanomaterials, where the two different carbon networks with sp3 and sp2 hybridization coexist, interacting and even transforming into one another. The extraordinary physiochemical properties defined by the unique electronic band structure of the two border nanoallotropes ensure the immense application potential and versatility of these all-carbon nanomaterials. The review summarizes the status quo of sp2 - sp3 nanomaterials, including graphene/graphene-oxide-nanodiamond composites and hybrids, graphene/graphene-oxide-diamond heterojunctions, and other sp2-sp3 nanocarbon hybrids for sensing, electronic, and other emergent applications. Novel sp2-sp3 transitional nanocarbon phases and architectures are also discussed. Furthermore, the two-way sp2 (graphene) to sp3 (diamond surface and nanodiamond) transformations at the nanoscale, essential for innovative fabrication, and stability and chemical reactivity assessment are discussed based on extensive theoretical, computational and experimental studies.